JavaScript Array.find Regex

Question

I have 2 arrays of keywords. I need to figure out the index of the first keyword in array 1 that matches any of the keywords in array 2.

Examples

array1 = ['spinach', 'avocado', 'milk', 'beans', 'ham', 'eggs', 'cheese'];
array2 = ['cheese', 'milk'];

In this example, milk at index 2 would be the first match, and I want to return the index of 2.

Can I use array.find() to return the index of the first match, if each element is compared to array2 using regex?

Answer 1

You could use Array#findIndex and check the second array with Array#includes.

var array1 = ['spinach', 'avocado', 'milk', 'beans', 'ham', 'eggs', 'cheese'],
    array2 = ['cheese', 'milk'];
    
console.log(array1.findIndex(v => array2.includes(v)));

Answer 2

You can find matching index using findIndex() and includes():

let index = array1.findIndex(s => array2.includes(s));

Demo:

let a1 = ['spinach', 'avocado', 'milk', 'beans', 'ham', 'eggs', 'cheese'],
    a2 = ['cheese', 'milk'];

let index = a1.findIndex(s => a2.includes(s));

console.log(index);

Docs:

• Array.prototype.findIndex()
• Array.prototype.includes()
• Arrow Functions