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:
- 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: In this example, we are getting the key of the given matched condition and printing the result in the console.
// Defining Lodash variable
const _ = require('lodash');
let 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
ArnavExample 2: In this example, we are getting the key of the given matched condition and printing the result in the console. and returning undefined for values that don't exist.
// Defining Lodash variable
const _ = require('lodash');
let 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
ArnavNote: This will not work in normal JavaScript because it requires the lodash library to be installed and can be installed using npm install lodash.