JavaScript: Get all indices of values in an array

JavaScript fundamental (ES6 Syntax): Exercise-216 with Solution

Write a JavaScript program to get all val indices in an array. If val never occurs, return [].

• Use Array.prototype.reduce() to loop over elements and store indexes for matching elements.

Sample Solution:

JavaScript Code:

//#Source https://bit.ly/2neWfJ2 
const indexOfAll = (arr, val) => arr.reduce((acc, el, i) => (el === val ? [...acc, i] : acc), []);

console.log(indexOfAll([1, 2, 3, 1, 2, 3], 1));
console.log(indexOfAll([1, 2, 3], 4));

Sample Output:

[0,3]
[]

Pictorial Presentation:

Flowchart:

Live Demo:

See the Pen javascript-basic-exercise-216-1 by w3resource (@w3resource) on CodePen.

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