JavaScript - Array every() Method


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Description

JavaScript array every method tests whether all the elements in an array passes the test implemented by the provided function.

Syntax

Its syntax is as follows −

array.every(callback[, thisObject]);

Parameter Details

  • callback − Function to test for each element.

  • thisObject − Object to use as this when executing callback.

Return Value

Returns true if every element in this array satisfies the provided testing function.

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 the following code at the top of your script.

if (!Array.prototype.every) {
   Array.prototype.every = 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))
         return false;
      }
      return true;
   };
}

Example

Try the following example.

<html>
   <head>
      <title>JavaScript Array every Method</title>
   </head>
   
   <body>   
      <script type = "text/javascript">
         if (!Array.prototype.every) {
            Array.prototype.every = 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))
                  return false;
               }
               return true;
            };
         }
         function isBigEnough(element, index, array) {
            return (element >= 10);
         }
         var passed = [12, 5, 8, 130, 44].every(isBigEnough);
         document.write("First Test Value : " + passed ); 
         
         passed = [12, 54, 18, 130, 44].every(isBigEnough);
         document.write("Second Test Value : " + passed ); 
      </script>      
   </body>
</html>

Output

First Test Value : falseSecond Test Value : true
javascript_arrays_object.htm

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