Replace item in array with indexOf Method in JavaScript

Last Updated On Sunday 10th Apr 2022

replace item in array javascript

The Most popular way to replace an element in an array is to use its index. If you know the index of the element you want to replace, you can update it.

	const frameworks = [
  'Angular', // Index 0
  'ReactJS', // Index 1
  'VueJS', // Index 2
]

frameworks[0] = 'Angular'

console.log(frameworks)
// Output: [ 'Angular', 'ReactJS', 'VueJS']
	

replace item in array using indexOf method

If you don’t know the item’s index you want to replace, you can use the JavaScript indexOf method to find it.

  • The indexOf function helps you find the framework’s index.
  • If the element doesn’t present in the array, the index returned is -1.
	const frameworks = [
  'Angular', // Index 0
  'ReactJS', // Index 1
  'VueJS', // Index 2
]

const findIndex = frameworks.indexOf('Angular')

console.log(findIndex) //  Output: 0

const nextJSIndex = frameworks.indexOf('NextJS')

console.log(nextJSIndex) //  Output: -1
	
	const frameworks = [
  'Angular', // Index 0
  'ReactJS', // Index 1
  'VueJS', // Index 2
]

const lastIndex = frameworks.indexOf('VueJS')

console.log(lastIndex)
// Output: 2

if (lastIndex !== -1)
  frameworks[lastIndex] = 'NextJS'

console.log(frameworks)
// Output: [ 'Angular', 'ReactJS', 'NextJS']

console.log(frameworks[lastIndex])
// Output: 'NextJS'
	

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