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JavaScript - When Closures, Loops, Function References, And Anonymous Functions Interact
Hey all,
I am confused about the true difference between the two below examples. Code: first example:
// Demonstrating a problem with closures and loops
var myArray = [“Apple”, “Car”, “Tree”, “Castle”];
var closureArray = new Array();
// Loop through myArray and create a closure for each that outputs that item
for (var i = 0; i < myArray.length; i++) {
var theItem = myArray[i];
closureArray[i] = function() {
document.write(theItem + “ < br / > ”);
}
}
// Loop through the closures and execute each one.
for (var i = 0; i < closureArray.length; i++) {
closureArray[i]();
}
Here we iterate through the length of myArray, assigning the current index of myArray to theItem variable. We declare closureArray 4 times as an anonymous function. The anonymous function in turn declares the predefined write() function, which is passed parameters. Since write() is in closureArray() a closure is created??? During each iteration, theItem is reassigned its value. The four closures reference this value. Since they reference this same value and since this value is reassigned ultimately to the value of the fourth index position, tHe time we execute closureArray later on, all four closures output the same string. This is because all four closures are within the same scope "the same environment" and therefore are referencing the same local variable, which has changed. I have a couple of problems with this example: 1) I thought a closure is a function that is returned - the inner function is not returned above. 2) theItem is not even a local variable of the parent function (closureArray) - I thought in order for a closure to work, the inner function only accesses the local variables of the outer function, but in this case the local variable is defined OUTSIDE of the parent function. 3) The guy says the "the four closures are sharing the same environment." The thing is even in the second example, they are sharing the same environment. Second example: Code: // A correct use of closures within loops
var myArray = [“Apple”, “Car”, “Tree”, “Castle”];
var closureArray = new Array();
function writeItem(word) {
return function() {
document.write(word + “ < br / > ”);
}
}
// Loop through myArray and create a closure for each that outputs that item
for (var i = 0; i < myArray.length; i++) {
var theItem = myArray[i];
closureArray[i] = writeItem(theItem);
}
// Loop through the closures and execute each one.
for (var i = 0; i < closureArray.length; i++) {
closureArray[i]();
}
Here we iterate over the length of myArray (4 times), assigning the index of myArray to theItem variable. We also return a function reference to the closureArray during each iteration (closureArray[i]), where i is index number so we assign 4 functon references. So when we iterate through myArray, we immediatelly call the writeItem() fucntion passing an argument of theItem at its current value. This returns a child anonymous function and when that child function is called, it will execute a block that calls the predefined write() method. We assign that returned anonymous function to the variable closureArray. Hence, closureArray holds a reference to that anonymous function. So closureArray during each iteration holds a reference to the anonymous function and we later call closureArray, which in turn calls the anonymous function, therefore calling the predefined write() function to output the local variable of the parent function. This outputs each distinct index of myArray. QUESTION: This is because since we created the closure, when we call writeItem, passing theItem argument, since theItem is a local variable of the parent function of the closure, it is never destroyed when we later call closureArray (the reference to the child anonymous function)? Yet weren't we using a closure in the first example as well? So whey wasn't those variables preserved? I don't think it has anything to do with assigning a returned anonymous function to closureArray. Even though an anonymous function creates a new memory position in the javascript engine, therefore not overwriting the other function references we create during the iteration, it's still referring to a local variable declared outside the reference. So if it's about the closure retaining value of parent's local variable even after exiting the parent function allowing for the current indexes to be preserved, then why did the closure in the first example fail to retain each index? Thanks for response Similar TutorialsHey all, I am having issues with below script. Firebug returns: form[0] is undefined [Break on this error] $(form[0].elements).each(function() { I have this under my form: <script> var thisForm = $('#validateForm'); thisForm.validation(); </script> Code: (function($) {
/*
Validation Singleton
*/
var Validation = function() {
var rules = {
email : {
check: function(value) {
if(value)
return testPattern(value,".+@.+\..+");
return true;
},
msg : "Enter a valid e-mail address."
},
url : {
check : function(value) {
if(value)
return testPattern(value,"https?://(.+\.)+.{2,4}(/.*)?");
return true;
},
msg : "Enter a valid URL."
},
required : {
check: function(value) {
if(value)
return true;
else
return false;
},
msg : "This field is required."
}
}
var testPattern = function(value, pattern) {
var regExp = new RegExp("^"+pattern+"$","");
return regExp.test(value);
}
return {
addRule : function(name, rule) {
rules[name] = rule;
},
getRule : function(name) {
return rules[name];
}
}
}
/*
Form factory
*/
var Form = function(form) {
var fields = [];
$(form[0].elements).each(function() {
var field = $(this);
if(field.attr('validation') !== undefined) {
fields.push(new Field(field));
}
});
this.fields = fields;
}
Form.prototype = {
validate : function() {
for(field in this.fields) {
this.fields[field].validate();
}
},
isValid : function() {
for(field in this.fields) {
if(!this.fields[field].valid) {
this.fields[field].field.focus();
return false;
}
}
return true;
}
}
/*
Field factory
*/
var Field = function(field) {
this.field = field;
this.valid = false;
this.attach("change");
}
Field.prototype = {
attach : function(event) {
var obj = this;
if(event == "change") {
obj.field.bind("change",function() {
return obj.validate();
});
}
if(event == "keyup") {
obj.field.bind("keyup",function(e) {
return obj.validate();
});
}
},
validate : function() {
var obj = this,
field = obj.field,
errorClass = "errorlist",
errorlist = $(document.createElement("ul")).addClass(errorClass),
types = field.attr("validation").split(" "),
container = field.parent(),
errors = [];
field.next(".errorlist").remove();
for (var type in types) {
var rule = $.Validation.getRule(types[type]);
if(!rule.check(field.val())) {
container.addClass("error");
errors.push(rule.msg);
}
}
if(errors.length) {
obj.field.unbind("keyup")
obj.attach("keyup");
field.after(errorlist.empty());
for(error in errors) {
errorlist.append("<li>"+ errors[error] +"</li>");
}
obj.valid = false;
}
else {
errorlist.remove();
container.removeClass("error");
obj.valid = true;
}
}
}
/*
Validation extends jQuery prototype
*/
$.extend($.fn, {
validation : function() {
var validator = new Form($(this));
$.data($(this)[0], 'validator', validator);
$(this).bind("submit", function(e) {
validator.validate();
if(!validator.isValid()) {
e.preventDefault();
}
});
},
validate : function() {
var validator = $.data($(this)[0], 'validator');
validator.validate();
return validator.isValid();
}
});
$.Validation = new Validation();
})(jQuery);
Hello everyone, I have been working on this function but no luck so far. Basically this is a simple vertical navigation menu, and I am just trying to to show or hide the sub-menus (unordered lists) with onmouseover & onmouseout. I can do this very easily with just css or inline events, but I'm just trying to figure it out the way I already set it up. So I am looping through the ULs first, then I loop through the LIs. Furthermore I find the right LI elements by checking their class names, and if they exist I trigger the onmouseover & onmouseout events on them so the ULs will appear/disappear. The issue is that this works only for the last list item because I am guessing of a closure. So instead of getting each item individually at each event, instead it gives me the last list item. I have searched the web for a while now about closures and such, but all the examples I find talk about nested functions and a single loop, which isn't my case because I have two loops and only one function. Any help would be appreciated. HTML Code: Code: <div id="navWrapper"> <ul> <li class="triggers"><a href="#">Item 1</a> <ul class="subMenu"> <li><a href="#">Item 1.1</a></li> <li><a href="#">Item 1.2</a></li> <li><a href="#">Item 1.3</a></li> </ul> </li> <li class="triggers"><a href="#">Item 2</a> <ul class="subMenu"> <li><a href="#">Item 2.1</a></li> <li><a href="#">Item 2.2</a></li> <li><a href="#">Item 2.3</a></li> </ul> </li> <li class="triggers"><a href="#">Item 3</a> <ul class="subMenu"> <li><a href="#">Item 3.1</a></li> <li><a href="#">Item 3.2</a></li> <li><a href="#">Item 3.3</a></li> </ul> </li> </ul> </div> Javascript Code: Code: <script type="text/javascript">
function hoverSh () {
var navWrap = document.getElementById('navWrapper');
var uls = navWrap.getElementsByTagName('ul');
var listItems = navWrap.getElementsByTagName('li');
for (var i=0; i<uls.length; i++) {
if (uls[i].className == "subMenu") {
var theUls = uls[i];
for (var j=0, c=listItems.length; j<c; j++) {
if (listItems[j].className == "triggers") {
var theItems = listItems[j];
theItems.onmouseover = function () {//alert(this.nodeName + i);return false;
theUls.style.display = 'block';
}
theItems.onmouseout = function () {
theUls.style.display = 'none';
}
}//end inner if
}//end inner loop w/ j
}//end if
}//end outer loop w/ i
}
window.onload = hoverSh;
</script>
Any links pointing to simplified tutorials on closures would be helpful too. I thought I understood them but I guess not! Am I doing something wrong here? I have two anonymous functions to validate two different forms on two different pages. They both work on the individual page, though when I try and put them in the same script.js folder only the top function seems to work. Code: <script type="text/javascript">
// Form Validation / Catalog Template ----------------------------------------------------------------------------------------------------------------------
document.getElementById("formValidation").onsubmit = function(){
if(document.getElementById("reqAddrCont").value == ""){
document.getElementById("reqAddrCont").className = "error";
return false;
}if(document.getElementById("reqAddrName").value == ""){
document.getElementById("reqAddrName").className = "error";
return false;
}if(document.getElementById("reqAddr1").value == ""){
document.getElementById("reqAddr1").className = "error";
return false;
}if(document.getElementById("reqAddr6").value == ""){
document.getElementById("reqAddr6").className = "error";
return false;
}if(document.getElementById("reqAddrState").value == "0"){
document.getElementById("reqAddrState").className = "error";
return false;
}if(document.getElementById("reqAddrPost").value == ""){
document.getElementById("reqAddrPost").className = "error";
return false;
}if(document.getElementById("reqAddrPhone").value == ""){
document.getElementById("reqAddrPhone").className = "error";
return false;
}if(document.getElementById("reqAddrEMail").value == ""){
document.getElementById("reqAddrEMail").className = "error";
return false;
}else{
return true;
}
};
// Form Validation / New Account Template --------------------------------------------------------------------------------------------------------------------------
document.getElementById("formValidationAccount").onsubmit = function(){
if(document.getElementById("AcctName").value == ""){
document.getElementById("AcctName").className = "error";
return false;
}if(document.getElementById("AcctTitle").value == ""){
document.getElementById("AcctTitle").className = "error";
return false;
}if(document.getElementById("AcctCompany").value == ""){
document.getElementById("AcctCompany").className = "error";
return false;
}if(document.getElementById("AcctAddress1").value == ""){
document.getElementById("AcctAddress1").className = "error";
return false;
}if(document.getElementById("AcctAddress2").value == ""){
document.getElementById("AcctAddress2").className = "error";
return false;
}if(document.getElementById("AcctAddress6").value == ""){
document.getElementById("AcctAddress6").className = "error";
return false;
}if(document.getElementById("AcctState").value == "0"){
document.getElementById("AcctState").className = "error";
return false;
}if(document.getElementById("AcctPost").value == ""){
document.getElementById("AcctPost").className = "error";
return false;
}if(document.getElementById("AcctCountry").value == ""){
document.getElementById("AcctCountry").className = "error";
return false;
}if(document.getElementById("AcctPhone").value == ""){
document.getElementById("AcctPhone").className = "error";
return false;
}if(document.getElementById("AcctLogin").value == ""){
document.getElementById("AcctLogin").className = "error";
return false;
}if(document.getElementById("AcctLogin2").value == ""){
document.getElementById("AcctLogin2").className = "error";
return false;
}if(document.getElementById("AcctPassword").value == ""){
document.getElementById("AcctPassword").className = "error";
return false;
}if(document.getElementById("AcctPasswordDupe").value == ""){
document.getElementById("AcctPasswordDupe").className = "error";
return false;
}else{
return true;
}
};
</script>
Hi All, I'm trying to convert an anonymous function to a real function (nesting is getting out of hand), however the msg object becomes undefined after conversion. Here is the converted anonymous function which fails: https://gist.github.com/2587613 and here is the original anonymous function which works: https://gist.github.com/2587667 Any help would be greatly appriciated What I want to do is have a two-dimension array where some of the elements point to the value in another element. I have done this successfully in PHP using referfences (=&) and now I want to do it in JavaScript. My JS skills are limited but I found this post explaining how it can be done - http://stackoverflow.com/a/1687183 Here's the code from that - Code: Function.prototype.toString = function() {
return this();
}
var x = 1;
var y = function() { return x }
x++;
alert(y); // prints 2
It looks like it will do what I need to do. However, I want to use a two-dimension array, and if I try this it doesn't work - Code: for (var a = 2; a <= 5; a++)
for (var b = 1; b < a; b++)
matrix[a][b] = function() { return (matrix[b][a]) };
matrix is the two-dimension array which is alreay set up with some values. The two for loops are structured to fill in the rest of the values as references to existing values (it's a 5 x 5 array). The problem is coming from function() { return (matrix[b][a]) } because instead of the values for a and b being used in the creation of the anonymous function the actual variable names are used instead. Then later when I attempt to read one of the values setup by this it is "undefined" because the anonymous function is tries to return matrix[a][b] rather than matrix[4][2]. Can anyone help? Thanks! I created a For Loop and counter starts at 0, then increase in increments of 1 after each iteration of loop i run a command 1( add html code such as Code: <td>named (part)</td> <td class= 'num'>votes</td> Then create variable of named percent use totalV for value of sum parameter then i add html code of Code: <td class='num'>(percent%(</td> then i add a function named createBar(0 using race[0], name1, party1, and votes1 in parameter values this is my coding Code: for (var i=0; i < name.length; i++)
{
document.write("<tr>");
document.write("<td>" name[i] + "(" + party[i] + ")</td>");
document.write("<td class='num'>" + votes[i] + "</td>");
var percent=calcPercent(votes[i], totalV)
document.write("<td class='num'>(" + percent +"%)</td>");
createBar(party[i],percent)
document.write("</tr>");
}
document.write("</table>");
}
</script>
</head>
so any improvements or what i am missing in my functions. Hello, I'm hoping someone can help me with this. I have 3 pages that I need to put into my framework, they are products, shopping cart and billing. At the moment they work perfectly fine. Here is a live example - http://www.cems.uwe.ac.uk/~r4-george...g/products.php Now, I have a framework for a whole website that I need to put these pages into. (http://www.cems.uwe.ac.uk/~r4-george/wp4/index.php) The index uses a switch statement to go between pages. Here is the index.php PHP Code: <?php # index.php /* * This is the main page. * This page includes the configuration file, * the templates, and any content-specific modules. */ // Require the configuration file before any PHP code: require_once ('./modules/config.inc.php'); // Validate what page to show: if (isset($_GET['p'])) { $p = $_GET['p']; } elseif (isset($_POST['p'])) { // Forms $p = $_POST['p']; } else { $p = NULL; } // Determine what page to display: switch ($p) { case 'about': $page = 'about.inc.php'; $page_title = 'About This Site Again'; break; case 'products': $page = 'products.inc.php'; $page_title = 'Products on this site'; break; case 'this': $page = 'this.inc.php'; $page_title = 'This is Another Page.'; break; case 'that': $page = 'that.inc.php'; $page_title = 'That is Also a Page.'; break; case 'contact': $page = 'contact.inc.php'; $page_title = 'Contact Us'; break; case 'search': $page = 'search.inc.php'; $page_title = 'Search Results'; break; // Default is to include the main page. default: $page = 'main.inc.php'; $page_title = 'Site Home Page'; break; } // End of main switch. // Make sure the file exists: if (!file_exists('./modules/' . $page)) { $page = 'main.inc.php'; $page_title = 'Site Home Page'; } // Include the header file: include_once ('./includes/header.inc'); echo "<div id=\"content\">"; // Include the content-specific module: // $page is determined from the above switch. include ('./modules/' . $page); // Include the footer file to complete the template: include_once ('./includes/footer.inc'); ?> It uses the .inc.php files located in the modules folder to switch between pages. Here is my products.inc.php - PHP Code: <? include("includes/db.php"); include("includes/functions.php"); if($_REQUEST['command']=='add' && $_REQUEST['productid']>0){ $pid=$_REQUEST['productid']; addtocart($pid,1); header("location:shoppingcart.php"); exit(); } ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>Products</title> <script language="javascript"> function addtocart(pid){ document.form1.productid.value=pid; document.form1.command.value='add'; document.form1.submit(); } </script> </head> <body> <form name="form1"> <input type="hidden" name="productid" /> <input type="hidden" name="command" /> </form> <div align="center"> <h1 align="center">Products</h1> <table border="0" cellpadding="2px" width="600px"> <? $result=mysql_query("select * from products"); while($row=mysql_fetch_array($result)){ ?> <tr> <td><img src="<?=$row['picture']?>" /></td> <td> <b><?=$row['name']?></b><br /> <?=$row['description']?><br /> Price:<big style="color:green"> £<?=$row['price']?></big><br /><br /> <input type="button" value="Add to Cart" onclick="addtocart(<?=$row['serial']?>)" /> </td> </tr> <tr><td colspan="2"><hr size="1" /></td> <? } ?> </table> </div> </body> </html> This is EXACTLY the same code as the working example. The products get listed correctly but the problem I have is the 'Add to Cart' button fails to work. Live example - http://www.cems.uwe.ac.uk/~r4-george...php?p=products Everything is in the right directory. When I inspect the 'Add to Cart' button in chrome I get the following - Quote: Uncaught TypeError: Cannot set property 'value' of undefined addtocart index.php:51 (anonymous function)index.php:83 onclick Any help is really appreciated, I'm struggling to see what I have done wrong. I don't know whether it's a Javascript problem. If you need any of the code from other pages I can post it too. Thanks in advance. I've been going through this great tutorial on how to implement a type-ahead feature on a text field and there's something which hopefully you guys can explain. On the third page there is this function. Code: AutoSuggestControl.prototype.init = function () {
var oThis = this;
this.textbox.onkeyup = function (oEvent) {
if (!oEvent) {
oEvent = window.event;
}
oThis.handleKeyUp(oEvent);
};
};
What I don't understand is this line: this.textbox.onkeyup = function (oEvent) { I know about anonymous functions, but I don't know where the value for the parameter oEvent is going to come from. Can someone explain this? Thanks! :) Hello! I'm working with nested functions and trying to pass a 'this' value to an anonymous being used in an assignment for an event listener. Here's the basics of my code: Code: <div id='abc'></div>
<script type='text/javascript'>
var abc = function () {
this.myFunction = function() {
var myObj
myObj = document.createElement("input");
myObj.setAttribute("type", "button");
myObj.setAttribute("value", "Click Me");
myObj.addEventListener("click", function () {
this.doDing();
}, false);
document.getElementById('abc').appendChild(myObj);
}
this.doDing = function () { alert('ding'); }
}
var myInstance = new abc();
myInstance.myFunction();
</script>
So, this should plop a button inside our DIV and when clicked I'd like it to run the alert-ding; unfortunately it seems to want to run the function as defined under the buttons object which doesn't work out too well. Any suggestions? Thanks! Hello, Problem 1: I have a function and it sets a value to a certain number according to the input. However, I don't want the function to print out the value to the screen, but instead temporarily save it for me to use throughout the whole script. I am a newbie and please help me. For example, I make this code: function add1(x) { var x = x + 1 return x; } and I call the function: add1(0); document.write("value = " + x + "<BR>"); Whenever I do this, document.write doesn't print out value = 1, it doesn't even print anything except for the headers, etc. Is there anyway to set the var x to be a value valid throughout the whole script instead of just the function itself? I really need help on this, thanks. Problem 2: I want to get a code working. Basically, I use a ram to "ram the gate". I set the damage done each turn, and the Gate's Health too. So for example, my ram's damage is 10 and the gate's health is 200. It would take 20 times to totally breach the gates(i.e., for gate health to become 0). When I use the following code, the total damage is the same throughout the whole looping until the gatehealth reaches 0 which makes it boring, is there anyway to modify or improve the script such that when I loop, the MiscDamage would be different for all the turns? thanks! Once again I apologize for asking such a noob-ish and very strange.... question. Quote: <script language="JavaScript" type="text/javascript"> <!-- // Begin function RamGates(Ram, Attack, Gate) { //introducing variables to be used var BaseDamage = 0; var FullDamage = 0; var MiscDamage = 0; var TotalDamage = 0; var GateHealth = 0; switch (Ram) { //ignore this part just comparing ram types case "Explosive": BaseDamage="10"; break; case "Wooden": BaseDamage="20"; break; case "Steel": BaseDamage="30"; break; case "", "?": default: BaseDamage="Failed to recognize Ram"; } switch (Attack) { //ignore this just comparing attack values case 0: FullDamage = BaseDamage; break; case 1: FullDamage = (BaseDamage*2)-8; break; case 2: FullDamage = (BaseDamage*2)-6; break; case 3: FullDamage = (BaseDamage*2)-4; break; case 4: FullDamage = (BaseDamage*2)-2; break; case 5: FullDamage = BaseDamage*2; break; case "", "?": default: FullDamage="Failed to recognize Attack"; } switch (Ram) { //this part is what i need help on, i need the loop function to keep using this to generate different "lucky damages" each time to make it interesting, i.e., first ram = 11 second ram = 16 third ram = 14 and so on..... case "Explosive": MiscDamage = Math.floor(Math.random()*21+10); break; case "Wooden": MiscDamage = Math.floor(Math.random()*6+0); break; case "Steel": MiscDamage = Math.floor(Math.random()*11+5); break; case "", "?": default: MiscDamage="Failed to recognize Ram"; } switch (Gate) { //ignore this part just comparing gate types to generate gate health case "Wooden": GateHealth = 50; break; case "Brick": GateHealth = 75; break; case "Small Stone": GateHealth = 90; break; case "Large Stone": GateHealth = 120; break; case "Granite": GateHealth = 140; break; case "Iron": GateHealth = 175; break; case "R Iron": GateHealth = 190; break; case "Thick Iron": GateHealth = 210; break; case "Steel": GateHealth = 230; break; case "R Steel": GateHealth = 250; break; case "Thick Steel": GateHealth = 275; break; case "Steel Iron Mix": GateHealth = 280; break; case "Thick Steel Iron Mix": GateHealth = 300; break; case "Strong Ruby Steel Mix": GateHealth = 400; break; case "Strong Sapphire Steel Mix": GateHealth = 450; break; case "R Thick Large Diamond Steel Mix": GateHealth = 500; break; case "", "?": default: GateHealth = "Failed to recognize Gate"; } TotalDamage = FullDamage + MiscDamage; with (document) { write ("Soldiers, " + "RAM THE GATES!" + "<BR>"); } while (GateHealth >= 0) //loops until gate health is lower than 0 { //need help! how to make it such that the loop will rerun the switching of ram for generating random misc(lucky) damages document.write ("Lucky Damage done = " + MiscDamage + "<BR>"); document.write ("Total Damage done = " + TotalDamage + "<BR>"); var GateHealth = GateHealth - TotalDamage document.write("Current GateHealth = " + GateHealth + "<BR>"); } } RamGates("Explosive", 5, "R Thick Large Diamond Steel Mix"); //function calling // End --> </script> I've now got to form an average of snowfall inputs, taken from looped prompts, however I'm not allowed to use arrays or functions... Almost every example I see uses arrays, such as this one he http://www.codingforums.com/showthread.php?t=4313 Is it possible to not use arrays to form the average? Please describe how to do this in general terms, as was highlighted in that link ^^^ I want to learn, not copy, although one can be derived from the other... What I haveso far, assume all vars have been announced. Code: for (var d=1; d<=numofinputs; d=d+1)
{
input = prompt("Enter a data input" + d)
}
Is it possible I'm attempting this in too general a manner? ie, running before I can walk. I want to learn javascript and I found codecademy.com which seems like a great way to learn the language. Before the first lesson it says Quote: You should be comfortable with loops, if statements, functions, and objects before attempting this course. Can someone explain what these are or point me in the direction where I can find the answers? I tried searching with google, but I havent found anything that clearly states what exactly the loop, object, etc. is. We have created this function with loops and arrays Problem is the loops work only when I take out the function when the function is in place, nothing works, it is part of exercise anyone have suggestions here is my code Code: title>Congressional Races</title>
<link href="results.css" rel="stylesheet" type="text/css" />
<script type="text/javascript" src="votes.js"></script>
<script type="text/javascript">
function totalVotes(votes){
var total=0;
for (var i = 0; i <votes1.length; i++) {
total = total + votes1[i];
}
document.write(total);
}
</script>
}
</head>
<body>
thanks all who can help Hi everyone, i thought about following code snippet: Code:
var newfunc = function() {
//...
}
func = (function (oldfunc,newfunc) {
return function () {
oldfunc();
newfunc();
}
}(func || function(){},newfunc))
There is a function "func" and with the above method i want to add a new function "newfunc" to this function, so when i call "func" in the futur, both functions will be executed. It works good, but suppose i want to add multiple functions to func, each time with the described method...could there be a problem with the stack? As far as i understand, the program creates something like a wrapper-function each time, that contains the two functions it combines. So in the case of adding 3 functions, a call of "func" would lead to this: call "wrapper 2", call "wrapper 1", call func1, call func2, call func3, call func 4. The really poor graphic should illustrate what i mean __________ F1|....|....| __|W1|....| F2|....|....| __|___|W2| ...|F3 |....| ...|___|___| ..........| F4| ..........|___| Has anyone an idea, if my thoughts on that are correct oder if this behaviour could be a problem? And is there probably a better way to combine functions, so that all functions would be in one column? Thanks and Greetings! moon-safari Note: major noobage here I'm sure... but can't seem to figure this out... How do I make these three functions into one script? Much love if you can help! Code: <script type="text/javascript">
setTimeout('yourFunction();', 2500);
function yourFunction(){
document.getElementById('hide').style.display='block';
}
</script>
<script type="text/javascript">
setTimeout('yourFunction2();', 8000);
function yourFunction2(){
document.getElementById('hide').style.position='fixed';
}
</script>
<script type="text/javascript">
setTimeout('yourFunction3();', 8500);
function yourFunction3(){
document.getElementById('hide').style.margin='0 -310px';
}
</script>
<script type="text/javascript">
setTimeout('yourFunction4();', 15500);
function yourFunction4(){
document.getElementById('hide').style.margin='0 610px';
}
</script>
Hi, I would like to do something like this: Code: function searchLocations(count) {
var found = false;
var input = document.getElementById('autocomplete').value;
var inp = input.toLowerCase();
var count = 0;
for (var j = 0; j < gmarkers.length; j++) {
gmarkers[j].hide();
var str=gmarkers[j].myname.toLowerCase();
var patt1=inp;
if (str.match(patt1))
{
found = true;
gmarkers[j].show();
count++;
}
}
if (count==1)
myclick(j);
if (count>1)
centerZoom();
if ( ! found ) alert("No matches found. Please check your spelling or refine your search.");
}
on this page here, but the functions - myclick(j); and centerZoom(); aren't getting called. I tried it with switches here, but that only made things worse. I know the functions work because if I put them two } up, they get called, but that takes them out of the if statements. Those if (count...) statements have to be where they are so that "count" will get the right value. Any ideas? I tried a a few tutorials but still can't get it, can any simply closures please?
I get programming. Really, I do. But this closure thing has me lost and needing a nice, simple explanation. Here's the code from the dojo tutorial: <script type="text/javascript"> dojo.require("dijit.form.Button"); // this is just to make the demo look nicer var arrFruit = ["apples", "kiwis", "pineapples"]; function populateData() { dojo.forEach(arrFruit, function(item, i) { var li = dojo.doc.createElement("li"); li.innerHTML = i + 1 + ". " + item; dojo.byId("forEach-items").appendChild(li); }); } </script> It is the anonymous function(item, i) that is perplexing me. As I see it, this use is not CREATING a function. It is calling a function called "function." Clearly, I am not up-to-speed. I am confounded as to how, within function(), "item" is KNOWN to refer to the value of the array element, and "i" is KNOWN to refer to the current element in the dojo.forEach() function. In my mind, I see a call to function, trying to pass parameters to it which were never defined above. The way I see it is: function myfunction(item, i) {code here} myfunction(this, that); In this example, I would get an error because "this" and "that" are not defined. Help, please!!! |
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