How to use array every in JavaScript

In this article I am going to explain every() in JavaScript.
  • 1915

Every method in JavaSript

JavaScript every method checks whether a define callback function returns true for all element in an array.

Syntax of every method

array.every(callback[, thisArgs);

 

Parameters in every method:

  • arrary

    Array required an array object.
     

  • callback

    Callback function accepts up to three arguments, and callback function is used to test  for each element
     

  • thisArgs

    ThisArgs is used as this when executing callbacks.


Return value in every method

It returns true if callback function is returned true for all array element, otherwise it returns false.

 

Exception in every method

If callback argument is not a function object, A TypeError exception is fire.

There are the following callback parameter:
 

Parameter Value
value Array element value.
index Number of index of the array element.

Example of every method

<html>

<head>

<title>JavaScript every method</title>

</head>

<body>

<script type="text/jscript">

    function CheckIfEven(value, index, ar) {

        document.write(value + " ");

 

        if (value % 2 == 0)

            return true;

        else

            return false;

    }

    var numbers = [2, 4, 5, 6, 8];

 

    if (numbers.every(CheckIfEven))

        document.write("All are even.");

    else

        document.write("Some are not even.");

</script>

</body>

</html>


Output:
 

2,4 some are not even.


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