Programming for beginners: JavaScript: array: every: Check for condition

‘every’ method return true, if all elements in the array satisfy given predicate, else false.

Syntax

arr.every(callback[, thisArg])

callback is a function that takes following three arguments.

Argument	Description
currentValue	The current element being processed in the array.
index	The index of the current element being processed in the array.
array	The array that every() is beingcalled upon.

thisArg

Optional. Value to use as this when executing callback.

function even(num){

return ((num%2) == 0);

}

arr1.every(even); // Return true if every element of array is even, else false.

every.html

<!DOCTYPE html>

<html>

<head>
    <title>Array every</title>
</head>

<body>
    <script type="text/javascript">
        var arr1 = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
        var arr2 = [2, 4, 6, 8];

        function even(num) {
            return ((num % 2) == 0);
        }

        document.write("Is all numbers even in arr1 : " + arr1.every(even) + "<br />");
        document.write("Is all numbers even in arr2 : " + arr2.every(even));
    </script>
</body>

</html>

Open above page in browser, you will get following text.

Is all numbers even in arr1 : false

Is all numbers even in arr2 : true

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Programming for beginners

Saturday 15 September 2018

JavaScript: array: every: Check for condition

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