How to implement a filter() for Objects in JavaScript?
The filter() method basically outputs all the element object that pass a specific test or satisfies a specific function. The return type of the filter() method is an array that consists of all the element(s)/object(s) satisfying the specified function.
Syntax:
var newArray = arr.filter(callback(object[, ind[, array]])[, Arg])
Parameters:
- Callback is a predicate, to test each object of the array. Returns True to keep the object, False otherwise. It takes in three arguments:
- Object: The current object being processed in the array.
- ind (Optional): Index of the current object being processed in the array.
- array (Optional): Array on which filter was called upon.
- Arg (Optional): Value to use(.this) when executing callback.
Example 1:
<script> var array = [-1, -4, 5, 6, 8, 9, -12, -5, 4, -1]; var new_array = array.filter(element => element >= 0); document.write( "<h2>Output\n</h2>", "<h3>", new_array, "</h3>"); </script> |
Output:
The above example returns all the positive elements in a given array.
Example 2:
<script> var employees = [ {name: "Tony Stark", department: "IT"}, {name: "Peter Parker", department: "Pizza Delivery"}, {name: "Bruce Wayne", department: "IT"}, {name: "Clark Kent", department: "Editing"} ]; var output = employees.filter(employee => employee.department == "IT"); for(var i=0;i<output.length;i++){ document.write("<h2>", output[i].name, "</h2>", "<br/>") }; </script> |
Output:
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