JavaScript - Array forEach() Method

Description

Javascript array forEach() method calls a function for each element in the array.

Syntax

Its syntax is as follows −

array.forEach(callback[, thisObject]);

Parameter Details

callback − Function to test for each element of an array.
thisObject − Object to use as this when executing callback.

Return Value

Returns the created array..

Compatibility

This method is a JavaScript extension to the ECMA-262 standard; as such it may not be present in other implementations of the standard. To make it work, you need to add following code at the top of your script.

if (!Array.prototype.forEach) {
   Array.prototype.forEach = function(fun /*, thisp*/) {
      var len = this.length;
      if (typeof fun != "function")
      throw new TypeError();
      
      var thisp = arguments[1];
      for (var i = 0; i < len; i++) {
         if (i in this)
         fun.call(thisp, this[i], i, this);
      }
   };
}

Example

Try the following example.

Live Demo

<html>
   <head>
      <title>JavaScript Array forEach Method</title>
   </head>
   
   <body>   
      <script type = "text/javascript">
         if (!Array.prototype.forEach) {
            Array.prototype.forEach = function(fun /*, thisp*/) {
               var len = this.length;
               
               if (typeof fun != "function")
               throw new TypeError();
               
               var thisp = arguments[1];
               for (var i = 0; i < len; i++) {
                  if (i in this)
                  fun.call(thisp, this[i], i, this);
               }
            };
         }
         function printBr(element, index, array) {
            document.write("<br />[" + index + "] is " + element ); 
         }
         [12, 5, 8, 130, 44].forEach(printBr);
      </script>      
   </body>
</html>

Output

[0] is 12
[1] is 5
[2] is 8
[3] is 130
[4] is 44

javascript_arrays_object.htm

Previous Page Print Page Next Page