The Lodash _.findLastKey() Method is like the _.findKey() method except that it iterates over elements of a collection in the opposite order.
Syntax:
_.findLastKey( object, predicate_function)
Parameters: This method accepts two parameters as mentioned above and described below:
- object: This parameter holds the object to find in.
- predicate_function: Function that is invoked per iteration.
Return Value: This method returns the key of the matched element, else undefined.
Example 1:
Javascript
// Defining Lodash variable const _ = require('lodash'); var users = { 'Ram': { 'mark': 100, 'status': "pass" }, 'Shyam': { 'mark': 90, 'status': "pass" }, 'Arnav': { 'mark': 50, 'status': "fail" } }; console.log(_.findLastKey(users, function(s) { return s.mark > 80; })); console.log(_.findLastKey(users, { 'mark': 100, 'status': "pass" })); console.log(_.findLastKey(users, ['status', "fail"])); console.log(_.findLastKey(users, 'status')); |
Output:
Shyam Ram Arnav Arnav
Example 2: returns undefined for values that don’t exist.
Javascript
// Defining Lodash variable const _ = require('lodash'); var users = { 'Ram': { 'mark': 100, 'status': "pass" }, 'Shyam': { 'mark': 90, 'status': "pass" }, 'Arnav': { 'mark': 50, 'status': "fail" } }; console.log(_.findLastKey(users, function(s) { return false; })); console.log(_.findLastKey(users, { 'mark': 100, 'status': "fail" })); console.log(_.findLastKey(users, ['status', ""])); console.log(_.findLastKey(users, 'mark')); |
Output:
undefined undefined undefined Arnav
Note: This will not work in normal JavaScript because it requires the lodash library to be installed and can be installed using npm install lodash.
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