Searching an element in Javascript Array

Javascript provides a collection of functions that you can use to find elements in an array. Let's start with the most basic one. The indexOf function goes through the entire array and returns the index of the element you searched for, if it is found else it returns -1. For example,

Example

let people = ["Harry", "Martha", "John", "Sam"];
console.log(people.indexOf("John"))
console.log(people.indexOf("Jim"))

Output

This will give the output −

2
-1

There are other, more complex functions that you can use to make search more powerful. Let's look at find() method. The find() method returns the first object matching the condition you provide it as the callback() method. For example,

Example

let people = [{
   name: 'Agnes',
   age: 25
}, {
   name: 'Richard',
   age: 21
}, {
   name: 'Zoe',
   age: 35
}];
let personNameStartsWithR = people.find(person => person.name[0] === 'R');
console.log(personNameStartsWithR)

Output

This will give the output −

{ name: 'Richard', age: 21 }

But above result gives us an object. We can find the index of this object using the findIndex function. For example,

Example

let people = [{
   name: 'Agnes',
   age: 25
}, {
   name: 'Richard',
   age: 21
}, {
   name: 'Zoe',
   age: 35
}];
let personNameStartsWithR = people.findIndex(person => person.name[0] === 'R');
console.log(personNameStartsWithR)

Output

This will give the output −

1

Note that the find() and findindex() functions take the callback as an argument and the callback takes arguments: element, index, array. These functions only give the first occurrence of the element. The indexOf function also takes another parameter, fromIndex, so that you can continue search from that point onwards. For example,

Example

let people = ["Harry", "Martha", "John", "Sam", "Martha"];
console.log(people.indexOf("Martha"));
console.log(people.indexOf("Martha", 3))

Output

This will give the output −

1
4

Sharon Christine

Published on 26-Jun-2018 14:25:27

• Related Questions & Answers
• Adding an element in an array using Javascript
• Removing an element from an Array in Javascript
• Searching in a sorted 2-D array in JavaScript
• Searching for values in an Javascript Binary Search Tree
• Finding the majority element of an array JavaScript
• How to search for an element in JavaScript array?
• Inserting element at falsy index in an array - JavaScript
• Finding the first redundant element in an array - JavaScript
• Searching for target string in a strangely sorted array in JavaScript
• Finding missing element in an array of numbers in JavaScript
• How to validate if an element in an array is repeated? - JavaScript
• JavaScript code to print last element of an array
• An element inside another element in JavaScript?
• Constructing an array of addition/subtractions relative to first array element in JavaScript
• Searching objects by value in JavaScript