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Array filter() method with example in JavaScript
JavaScript filter() method: Here, we are going to learn about the filter() method of array in JavaScript.
Submitted by IncludeHelp, on March 02, 2019
JavaScript filter() method
filter() method is used to returns an array with the values which pass the given test (condition).
Syntax:
array.filter(function, [value]);
Parameters: A function name and an optional value to be tested with all elements.
Ref: JS Array filter() function
Return value: An array with the values which pass the test (match the condition)
Example:
Input:
var numbers = [10, -10, 20, -20, 30, -30, 0, -1];
//function to check positive numbers
function isPositive(n){
return n>=0;
}
//function to check negative numbers
function isNegative(n){
return n<0;
}
Function call:
var positive_numbers = numbers.filter(isPositive);
var negative_numbers = numbers.filter(isNegative);
Output:
positive_numbers: 10,20,30,0
negative_numbers: -10,-20,-30,-1
JavaScript code to create arrays of positive and negative numbers from an array using Array.filter() method
<html>
<head>
<title>JavaScipt Example</title>
</head>
<body>
<script>
//function to check positive numbers
function isPositive(n){
return n>=0;
}
//function to check negative numbers
function isNegative(n){
return n<0;
}
var numbers = [10, -10, 20, -20, 30, -30, 0, -1];
var positive_numbers = numbers.filter(isPositive);
var negative_numbers = numbers.filter(isNegative);
//printing arrays
document.write("numbers: " + numbers + "<br>");
document.write("positive_numbers: " + positive_numbers + "<br>");
document.write("negative_numbers: " + negative_numbers + "<br>");
</script>
</body>
</html>
Output
numbers: 10,-10,20,-20,30,-30,0,-1
positive_numbers: 10,20,30,0
negative_numbers: -10,-20,-30,-1
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