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JavaScript - Check Or Just Set Boolean?
This is perhaps a somewhat trivial point but it's bugged me a couple of times recently and I wondered if anyone out there had any thoughts on the matter.
Essentially I have an action that can happen many times but I want to record whether it has happened at least once. I know we are talking about a trivial amount of processing and code here but is there any real difference between the following two methods: Code: myCheck: false,
myRepeatedlyCalledFunction: function() {
this.myCheck = true;
// do some stuff
}
vs Code: myCheck: false,
myRepeatedlyCalledFunction: function() {
if(this.myCheck === false) {
this.myCheck = true;
}
// do some stuff
}
thoughts? Similar Tutorialshi, I'm trying to modify this function: Code: function togglePoly(poly_num) {
if (document.getElementById(poly_num)) {
if (document.getElementById(poly_num).checked) {
gpolys[poly_num].show();
} else {
gpolys[poly_num].hide();
}
}
}
which works for a checkbox to one that works for a button. I guess I'm stuck on what to replace "checked" with there in the 3rd line. is there some one word answer, or do I need to I rewrite the function to be more button-friendly? thanks in advance So. When I save a boolean to localStorage It converts it to string. PHP Code: localStorage["fixedBackground"] = document.getElementById("fBackground").checked; And that saves a 'true' or 'false' string. So to convert it to a boolean value, in the 'restore options' I use the function 'toBool' PHP Code: function toBool(str) { if ("false" === str) return false; else return str; } PHP Code: var value = localStorage["fixedBackground"]; if (null != value) document.getElementById("fBackground").checked = toBool(value); And that works just fine. However, I want to recall this saved data in a javascript. I want an PHP Code: if (value = true){ document.getElementsByTagName('body')[0].style.backgroundAttachment="fixed"; } But I can't get a 'toBool' type of function into that statement This is my method of retrieving the data: PHP Code: var port = chrome.extension.connect({name: "knockknock"}); port.postMessage({get: "fixedBackground"}); port.onMessage.addListener(function(msg) { //Set bgimage attachment javascript:value=msg.value; which makes the full if statement: PHP Code: var port = chrome.extension.connect({name: "knockknock"}); port.postMessage({get: "fixedBackground"}); port.onMessage.addListener(function(msg) { //Set bgimage attachment javascript:value=msg.value; if(value = true) { document.getElementsByTagName('body')[0].style.backgroundAttachment="fixed"; } }); any ideas? I am about to translate some C++ code to JavaScript. In C++, it is straightforward to declare and use a Boolean variable; all I do is swap it between true and false and back again as needed. For example, Code: // C++ Code . . . bool na = 1; . . . na = !na; . . . I am wondering if JavaScript offers boolean variables. As far as I know, it does not, but I thought I would confirm by asking around. At the moment, I am planning to code the comparable block in Javascript using an "if" statement or a ternary operation. For example, Code: JavaScript Code . . . var na = 1; // Option 1 if (na) na = 0; else na = 1; // Option 2 na = ((na) ? 0 : 1); . . . Is one of these options recommended as the best way to simulate a boolean variable and operation? (I would like the fastest-executing code possible.) Or is there another--better--way to do it? All advice and recommendations appreciated. Thank-you in advance. Hello. If the function called Change has ever been called, the function in window onload is to not be executed. This is what I have so far, but I am sure it's wrong or missing something. I tried to confirm the results with document.write or alert but am having trouble doing so. Code: window.onload=function(){
if (calledAtLeastOnce == false) {
Change('big', 'http://www.adomainname.com/image.jpg');
}
}
function Change(id,src,w,h){
var calledAtLeastOnce = true;
}
Hi, I am very new to javascript and html. I am trying to create a function which will hide or show a div (div1). Right now, it is always showing the div whether the boolean value is true or false. I know that it is getting inside the else if part, but it doesn't seem to be working. Code: <script type="text/javascript">
function hideDiv(flag)
{
if (flag == false)
{
document.getElementById('div1').style.visibility="visible";
}
else if (flag == true)
{
document.getElementById(div1).style.visibility="hidden";
}
}
var bool = new Boolean(true)
hideDiv(bool);
</script>
<body>
<div id="div1">
Text!
</div>
</body>
Thank you for taking a look Hello everyone! I'm currently doing an assignment which involves a snack machine. I'm currently working on the PacketOfCrisp class. It needs to start with 10 crisps, and have a boolean field for whether or not it's closed. This field is called open and is obviously set to false when the object is created. It also needs to give out some messages, ie if the packet is not open then a message should appear saying that the packet is closed. If the pack has no crisps left a message should appear saying as such. Other than that when selecting eatCrisp the amount of crisps in the packet should go down by one. Here is what I have so far: Code: public void eatCrisp()
{
if(open = false) {
System.out.println("Open packet");
}
else if (open = true && numOfCrisps >= 1) {
numOfCrisps = numOfCrisps - 1;
}
else {
System.out.println("No Crisps!");
}
}
Now for some reason when I invoke eatCrisp it takes out a crisp and changes the "open" field of the object to true and I can't figure out why. As far as I can figure it should be giving me a message of "Open packet" until I open the packet with the "openPacket" method, but instead "eatCrisp" is doing that by itself. Any ideas? Hello fellow programmers, I am having some trouble with my javascript doing what I want it to, which is returning values (true/false || 1/0). I haven't used much javasript but I am experienced with C#, Java, Python etc so this is sort of new to me syntax wise. Here is what I have so far: http://jsfiddle.net/HpSyJ/1/ note: for some reason css doesn't like jsfiddle :S, the error messages are hidden in my Notepad++ & firefox combo though Really all I want is when I hit submit, it runs an alert or changes the error message to visible. Can someone please have a quick read over and see if anything jumps out at them? Thanks in advance, Andrew On this webpage http://www.corkdiscos.com/testimonials.html i have a like button. when a user clicks like a comment box appears. when i unlike the button the comment box disappears this is ok but when a user has already liked the facebook page and comes to my webpage the comment box does not show. so im looking for a piece of javascript to check if a user has like the button on my page and if so to show the comment box. please check my source code of the website http://www.corkdiscos.com/testimonials.html to see what i have so far. any help would be greatly appreciated Hi guys. I'm working a bunch of pre existing code on a CMS. Just after a quick fix. Doing a show/hide thing on a particular div somewhere on the page depending if a checkbox is ticked or not. Currently there is 3 checkboxes that are dynamically added through the CMS. Here's simplified version of the form: Code: <form id="simplesearch" name="simplesearch"> <input type="checkbox" onclick='showhidefield(this.value)' name="meta_data_array_search_criteria[custom_profile_type][]" value="5" class="input-checkboxes" /> <input type="checkbox" onclick='showhidefield(this.value)' name="meta_data_array_search_criteria[custom_profile_type][]" value="4" class="input-checkboxes" /> </form> And here's the javascript I was playing with. Code: function showhidefield(id)
{
if(document.simplesearch.meta_data_array_search_criteria[custom_profile_type][''].checked) {
document.getElementById("profile_fields_wrapper_" + id).style.visibility = "visible";
}
else
{
document.getElementById("profile_fields_wrapper_" + id).style.visibility = "hidden";
}
}
Problem I'm having is how do i do a check to see if those checkboxes are checked in the javascript with those name arrays? How do i separate them? 'm guessing I have to loop through them or something?Hopefully that make senses - it's late here and I'm losing the plot Any pointers would be gratefully welcomed I have a text input box that resets to blank when the user enters an alpha character, it also checks for the number 0 as it has to be greater than 0 too... when I submit the form it is blank the variable changes to blank (as I use parseInt to convert it to an integer at a later stage) What can I do to check and see if it is NaN value? (I've tried isNaN() and it did not do what I wanted it to) this code is supposed to ask the users name and say how many letters in it get 2 random numbers ask user to add them if right say Well Done! if wrong say Sorry, you are wrong. when i run this nothing comes up whats wrong? thanx Code: <script>
var firstName = "";
var numLetters = 0;
firstName = prompt("Hi, what's your first name?", "");
numLetters = firstName.length;
alert ("Did you know there are " + numLetters + " letters in your name?");
var num1 = Math.floor(Math.random()*9) + 1;
var num2 = Math.floor(Math.random()*9) + 1;
var answer;
var useranswer;
answer = num1+num2;
useranswer = promt("What is" + num1 + "+" + num2 + "?");
If (answer = useranswer)
{
alert("Well done!");
}
else
{
alert("Sorry, you are wrong.");
}
</script>
Is it possible to find out if an element is using a scroll bar for overflow? like I need to be able to change the size of something if there is any overflow.... I need to create some javascript code that asks a user a series of yes/no questions. Depending on how the user answers it will direct them to additional yes/no questions or simply stop with a message that they are not eligible. I need something similar to this site: http://www.kingfoundation.com/Grants...lity-Quiz.aspx Any help to develop this code would be much appreciated as I am a fairly inexperienced developer. i have an assignment to solve in which i have given two checkboxes one is enabled and another one is disabled n m required that if we select enable checkbox the disabled checkbox may also be selected automatically can any one help out for its coding please Thanks plz check bold part of function is not working. what is wrong with it.? Code: function onesizecheck(chk_id,siz) {
alert(chk_id);
if(document.getElementById('siz_check').value=='')
{
document.getElementById('siz_check').value=siz;
}//end if
if(document.getElementById('siz_check').value==siz) {
document.getElementById('siz_check').value=siz;
}
else {
alert('Multi size are not allowed.');
for(var i = 0; i < document.delet['checkbox[]'].length; i++){
var cb = document.getElementById('checkbox');
alert(cb[i].value);
}
}
}//end function
Hello, I have never used javascript before, so this might be a very basic question. I have a script on my blog which places a stumbleupon button on the page. This is the code that calls the script: Code: <script src="http://www.stumbleupon.com/hostedbadge.php?s=5"></script> Today I went to my blog and it was taking a long time to load, it turns out because stumbleupons site is down so the script can't be accessed. A whole lot of other stuff on the page just doesn't load until it times out though, so it takes like 3 minutes for the page to load. What I want to know is can I test if the script is reachable and only call it if it is, so that if there is a 403 or 404 error it just won't even try to load it and continue loading the rest of the page?? Any help is greatly apprectiated! Thanks. I got a page that gets created dynamically. sometimes I get images output with NO source like this Code: <img src="" id="md_1"> <img src="" id="md_2"> etc. etc. the image id are created dynamically also and always start with "0" and count up in order. I need to check everyone of those image links and when they are blank like above change the src to a default image. I have spent 8 hours on this one simple function and cannot seem to get it to work. I will call the function at the end of the page. I am trying to get a link that when clicked it will check all the checkboxes in my form. My problem is that my values are stored in an array: <INPUT TYPE=\"checkbox\" name=\"emailArray[]\" value=\"$email\"> print"<br><a href=\"#\" onClick=\"checkAll()\">check all</a><br>"; Here is my javascript function : function checkAll(){ alert('hi'); var df = document.selectEmailForm.elements; for (var i = 0; i < df.length; i++) { if (df[i].name == "emailArray[]" ) { document.selectEmailForm.emailArray[i].checked=true; } } } Any ideas? Any help is greatly appreciated. Thanks for your time! Hi, I am not familiar with javascript, I am using a check box validation tool that I copied from this site: http://mediazeal.com/checkbox-validator.htm This is my webpage: http://rbhlc.weebly.com/discover-hea...n-jyutsu.html# Right now when you click the buy now button (when the checkbox is checked) i does not go to the hyperlink. How can I get the button to go to my link when the checkbox is validated? Here is my code: (the authorize.net account it a Test Account.. so it won't link to anything sensitive) <form name="form" method="post" action="#" onSubmit="return checkme();"> <table cellpadding="0" cellspacing="0" border="0"> <tr> <td colspan="2" align="center"><input type="checkbox" name="agree" value="agree_terms"> I agree to the terms</td> </tr> <tr> <td colspan="2" align="center"> <form name="PrePage" method = "post" action = "https://scotest.authorize.net/payment/CatalogPayment.aspx"> <input type = "hidden" name = "LinkId" value ="3569f626-b8a8-4974-8ceb-35ca08a63087" /> <input type = "image" src ="//testcontent.authorize.net/images/buy-now-gold.gif" /> </form> </td> </tr> Thank you for your support. Hello, today I am trying to allow a user to easily uncheck/check all checkboxes in a form by checking or unchecking a checkbox. The checkboxes would be in a form like so: Code: <form action="" method="post"> <input type="checkbox" name="checked[]" value="1"> <input type="checkbox" name="checked[]" value="2"> <input type="checkbox" name="checked[]" value="3"> <input type="checkbox" name="checked[]" value="4"> </form> I use an event handler to call a function: Code: <input type="checkbox" name="checkall" onchange="checkall('checked[]', this.checked)">
And here is the function: Code: function checkall(box_name, current_state) {
all = document.getElementsByName(box_name);
action = (current_state == "checked") ? "false" : "true";
for (i = 0; i < all.length; i++) {
all[i].checked=action;
}
}
The event handler should pass the name of the checkboxes and whether the "check all" checkbox is currently checked or not to the checkall() function. Nothing happens when I check/uncheck the "check all" function. Help? |
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