Javascript Course

The code presented below can be used to highlight images on page when the user clicks on them then, if the user clicks again on that image, the highlight style is removed.
- The script adds CSS style with JavaScript: "padding", "background", and "border" to the image clicked by the user, when the user clicks again on that image, the highlight effect is removed.

Code of the script:

<script>
// set image properties, for Highlight effect added when click
var imgProp = {
 'padding': '3px',
 'backgroundColor': '#eded01',
 'borderSize': '1ps',
 'borderStyle': 'dashed',
 'borderColor': '#0001fe'
};

// function to highlight IMGs on click - from: https://coursesweb.net/
function highlightImg() {
 // gets all <img> tags, and their number
 var allimgs = document.getElementsByTagName('img');
 var nrallimgs = allimgs.length;

 // traverses the <img> elements, and register onclick to each one
 // else, apply the properties defined in $imgProp
 for(i=0; i<nrallimgs; i++) {
 allimgs[i].onclick=function() {
 // if borderStyle is already applied, anulates the 'padding', 'background' and 'border' properties
 if(this.style.borderStyle == imgProp.borderStyle) {
 this.style.padding = 'auto';
 this.style.background = 'none';
 this.style.border = 'none';
 }
 else {
 this.style.padding = imgProp.padding;
 this.style.backgroundColor = imgProp.backgroundColor;
 this.style.borderSize = imgProp.borderSize;
 this.style.borderStyle = imgProp.borderStyle;
 this.style.borderColor = imgProp.borderColor;
 }
 }
 }
}

// calls the highlightImg() function to apply the effect
highlightImg();
</script>
- In the imgProp object you can define the highlight style: "padding", "background", and "border" properties.
- The effect is for all the <img> tags in the page; if you want the highlight effect to be applied only to the images added into a specified HTML element, replace this code:
var allimgs = document.getElementsByTagName('img');
With this line of code ('idelm' is the ID of the element in which the images are included).
var allimgs = document.getElementById('idelm').getElementsByTagName('img');
- The JavaScript script must be added at the end of the HTML document, before the ending </body> tag.

• Demo, click on these images.
Robot     Love     Angel

Daily Test with Code Example

HTML
CSS
JavaScript
PHP-MySQL
What attribute makes a radio button or checkbox input selected?
checked="checked" selected="selected" disabled="disabled"
<input type="checkbox" name="a_name" value="value" checked="checked" />
What CSS value scales the background image to the largest size contained within the element?
repeat-x contain linear-gradient
#id {
  background:url("path_to_image.png");
  background-size:contain;
  background-repeat:no-repeat;
}
What operator is used to determine the rest of the division of two numbers?
% * /
var rest8_7 = 8 % 7;
alert(rest8_7);
Indicate the PHP function that rounds a number up to the next highest integer.
floor() ceil() abs()
$nr = ceil(3.5);
echo $nr;        // 4
Highlight Images on click

Last accessed pages

  1. PHP Method Chaining (2388)
  2. Animation of HTML elements with CSS (200)
  3. Convert XML to JSON in PHP (9772)
  4. Date and Time in ActionScript 3 (8568)
  5. TV-Screen shape with CSS (2550)

Popular pages this month

  1. Courses Web: PHP-MySQL JavaScript Node.js Ajax HTML CSS (62)
  2. JavaScript Course - Free lessons (43)
  3. Read Excel file data in PHP - PhpExcelReader (43)
  4. PHP-MySQL free course, online tutorials PHP MySQL code (38)
  5. HTML Course - Free Lessons (37)