JavaScript - jQuery - Ajax

Topics related to client-side programming language.
Post questions and answers about JavaScript, Ajax, or jQuery codes and scripts.

  1. » PloMar
    I want to display a file (image) in canvas before it is uploaded.
    The preview action in canvas should be executed all in the browser without...
    Last post » Admin
    You can use URL.createObjectURL() on the File from your <input> to generate a blob object URL.
    Generated URL will be like:...

  2. » PloMar
    I have a canvas element and a form with a text box and a button. I want to be able to put an image url into the text box, and after click on...
    Last post » Admin
    You can use this script. When click on the button, it adds the image from URL in page (into a Div, #pic1), then, the function addCnvImg() gets...

  3. » PloMar
    I have the following code:
    <img src="image.png" alt="Image" onclick="test(data)" />

    Last post » Admin
    If the argument is a string, you should add it between quotes, like this:
    <img src="image.png" alt="Image"...

  4. » PloMar
    Can I make the content of a html div to be editable?
    For example I have the following code:
    <div id="edit1">Content that can be...
    Last post » MarPlo
    To make the content of a html element to be editable, just add the: contentEditable="true" attribute in that tag. It can be used in almost...

  5. » PloMar
    I have an input text field to which i want to display a tooltip with a html table, when the mouse is over the input field.
    How can i make it...
    Last post » Admin
    Set "position:relative;" to the parent container (it is important for absolute position), then set "position: absolute;",...

  6. » PloMar
    How can I refresh the page after a specified time?
    I have a html table with data from server. These data are changed to every 3 minutes, so I want to...
    Last post » MarPlo
    You can use the reload() function added in setTimeout().
    // refresh page after 3 min. (true to load from server, not from cache)...

  7. » PloMar
    How can I parse the array items in reverse order, in JavaScript?
    I have a Div and an array with numbers in JS code, like this:
    Last post » MarPlo
    The simplest way is to use a reverse for() loop (with "i--").
    See this example:
    <div id="dv1"></div>

  8. » PloMar
    How to add (append) text in textarea using jquery without removing previous text?
    I have this code, but it only works for first time, when i change...
    Last post » MarPlo
    Inside the dom the value and text attributes are stored separately. When you use append the text is appended but the value is blanked because it is...

  9. » PloMar
    I'm drawing text in an HTML5 canvas on top of an image. I want to calculate a font size so that the string will span 200 pixels width.
    Last post » MarPlo
    The fillText() method has an optional fourth argument, which is the max width to render the string.
    - MDN's documentation says:
    maxWidth - the...

  10. » PloMar
    Hello all
    Anyone know how to calculate the number of characters that will fill one line of a div with a fixed width (for example 200px), using...
    Last post » MarPlo
    You can use this formula to get the width of the line for a given number of characters (CPL):
    Width = CPL * (font-size / font-constant)
    - CPL...

  11. » PloMar
    I use this code to animate position of a Div when is hovered. I move it with 2500 animation speed.
    How do I change speed of this animation to 800,...
    Last post » Admin
    Try with the dequeue() function (Execute the next function on the queue for the matched elements).
    <div id="dv">Animate...

  12. » PloMar
    Let say I have this html:
    <div id="parent">
    <div id="c1">Content child 1</div>
    Last post » Admin
    Try with the ">" selector, it refers to the direct childen.
    1. Example get array with the ID of all direct children.

  13. » PloMar
    How can I use JavaScript /jQuery to follow the mouse cursor with a DIV in the whole page?
    Last post » Admin
    If you want this effect with pure JavaScript, you can use this code:
    #div_moving {
    position: absolute;
    width: 140px;...

  14. » PloMar
    I'm playing with jQuery. Now I test the trigger() method.
    I try to trigger a custom method and pass two additional arguments (an object and a...
    Last post » Admin
    When you pass multiple arguments with trigger(), and those arguments aren't a number or a string, you should pass all the additional arguments into...

  15. » PloMar
    I have a Select box and options with IDs of the rows from a MySQL table.
    In that form there are 3 text fields.
    Now, when I select an option from the...
    Last post » Admin
    To make that script you need to know how to work with JavaScript /Ajax and with data in JSON format.
    1. Register an "onchange" event to the...

  16. » PloMar
    I have an object like this in javascript:
    var obj = {
    prop1: 'val 1',
    prop2: 'val 2',
    prop3: 'val 3'
    What is the best way to...
    Last post » Admin
    You can use the built in Object.keys method:
    var obj = {
    prop1: 'val 1',
    prop2: 'val 2',
    prop3: 'val 3'

    var props =...

  17. » PloMar
    I have an object like this in javascript:
    var obj = {
    prop1: 'val 1',
    prop2: 'val 2',
    prop3: 'val 3'
    What is the best way to...
    Last post » Admin
    To remove a property from a javascript object, you can use the "delete" instruction.
    var obj = {
    prop1: 'val 1',

  18. » MarPlo
    I have a html table and a button, like this:
    <table id="tb_id" border="1">
    Last post » Admin
    To append a row in a html table, use this syntax:
    $('#table_id > tbody:last').append('<tr>...</tr>');
    And to...

  19. » MarPlo
    I'm trying to dynamically add and remove items with jQuery when I press the Append /Remove buttons.
    This is the html code:
    Last post » Admin
    Use the append() and remove() jquery methods, like in this example:
    <ul id="lists">
    <li>List Item 0</li>

  20. » MarPlo
    I need to serialize an object to JSON in JavaScript. Is there a "standard" way to do this?
    I have an array defined something like this:...
    Last post » Admin
    Use the JSON object methods.
    - To convert an object to a string, use JSON.stringify() :
    var json_string = JSON.stringify(your_object, null, 2);...

  21. » MarPlo
    I want to do something like this:
    I wish to set...
    Last post » Admin
    Use the prop() method.
    $('.chkbox').prop('checked', true); // checking
    $('.chkox').prop('checked', false); // unchecking
    And if you...

  22. » MarPlo
    Is it posible to run a php function through a javascript function?
    Something like this:
    <div id="php_code">Here will be added the...
    Last post » Admin
    PHP is evaluated at the server; javascript is evaluated at the client-side/browser, thus you can't call a PHP function from javascript directly. But...

  23. » MarPlo
    Is there any way I can modify the URL of the current page without reloading the page?
    I only need to change the portion after the domain, when a...
    Last post » Admin
    You can use the history.pushState() method to change the url address without refreshing the page.
    It works in modern browsers which suport HTML5....

  24. » MarPlo
    I have written a code that adds a text in canvas on clicking a button.
    And i want to display this text for lets say 2 seconds. How can I make the...
    Last post » Admin
    You have to use setTimeout() to call a function, after a given time, that clears the canvas content.
    Here's a simple demo for writing and clearing...

  25. » MarPlo
    Hi all,
    How can I set the canvas dimensions (width and height) according to window's size, using JavaScript?
    And, if it's possible, to change canvas...
    Last post » Admin
    With self.innerWidth and self.innerHeight you can get the window's width and height. Then, with "resize" event you can detect when the...