Underscore.js filter() function

Underscore.js _.filter()

Underscore.js _.filter() is used to filter elements from a list that match certain condition.

The full function signature is _.filter(list, predicate, [context]).

The second function parameter “predicate” is a function that provides the filter logic.
 
The following example filters even numbers from an array.

<!DOCTYPE html>
<html>
    <head>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore.js"></script>
        
        <script type="text/javascript">
            var numbers = [1,2,3,4,5,6,7,8,9,10];
            
            var even_numbers = _.filter(numbers,function(n){
                return n % 2 == 0;
            });
            console.log(even_numbers);
        </script>
    </head>
    
</html>

Output :

underscorejs filter even numbers
 
Similarly, following example filters employees whose above is 30 using the _.filter() function and then iterates them using _.each() :

<!DOCTYPE html>
<html>
    <head>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore.js"></script>
        
        <script type="text/javascript">
            var employees = [{name:"Andy", age:21},
                             {name:"Bob", age:31},
                             {name:"Charlie", age:41}];
            
            var emp_above30 = _.filter(employees,function(emp){
                return emp.age > 30;
            });
            console.log("Employees above 30 are : ");
            _.each(emp_above30,function(emp,index){
                console.log(emp.name);
            });
        </script>
    </head>
    
</html>

Output :

underscorejs filter objects
 

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