Underscore.js _.omitWhen() Method

The _.omitWhen() method returns a copy of the object omitting those properties for which the given predicate function returns true. The predicate function is invoked with each property value.

Syntax:

_.omitWhen( Object_name, predicate_func );

Parameters:

• Object_name: Object from which the key/value pair is to be omitted.
• predicate_func: Given function which contains the conditions for properties is to be omitted

Return Value: This method returns a copy of the object after omitting properties.

Note: This will not work in normal JavaScript because it requires the underscore.js contrib library to be installed. 

Underscore.js contrib library can be installed using npm install underscore-contrib –save.

Example 1:

Javascript

// Defining underscore contrib variable
var _ = require('underscore-contrib');

var obj = {
    1: "Gfg1",
    2: "Gfg2",
    3: "Gfg3"
};

var val=_.omitWhen(obj, function (id)
         { return id == "Gfg2" });
console.log(val);

Output:

{ '1': 'Gfg1', '3': 'Gfg3' }

Example 2: If no property is found in the object, this method omits nothing.

Javascript

// Defining underscore contrib variable
var _ = require('underscore-contrib');

var obj = {
    1: "Gfg1",
    2: "Gfg2",
    3: "Gfg3"
};

var val=_.omitWhen(obj, function (id)
          { return id == "Gfg4" });
console.log(val);

Output:

{ '1': 'Gfg1', '2': 'Gfg2', '3': 'Gfg3' }