Find which array element exists in a string

Question

Is there any method or quick way to see which of the elements in an array exists in a string?

const myArray = ['foo', 'bar', 'baz'];
const myString = 'somelongbarstring';

In this example, bar from the array exists in myString, so I need to get bar given myArray and myString.

Jack Bashford · Accepted Answer · 2019-07-11T13:27:54.230

11

Use find with includes:

const myArray = ['foo', 'bar', 'baz'];
const myString = 'somelongbarstring';

const res = myArray.find(e => myString.includes(e));

console.log(res);

If you want to find all items included in the string, swap out find for filter:

const myArray = ['foo', 'bar', 'baz'];
const myString = 'somelongbarstring-baz';

const res = myArray.filter(e => myString.includes(e));

console.log(res);

If you want the index, use findIndex:

const myArray = ['foo', 'bar', 'baz'];
const myString = 'somelongbarstring';

const res = myArray.findIndex(e => myString.includes(e));

console.log(res);

Multiple indexes is a little tricky - you'd have to use the Array.prototype.keys method to preserve the original indexes because filter returns a new array with new indexes:

const myArray = ['foo', 'bar', 'baz'];
const myString = 'somelongbarstring-baz';

const res = [...myArray.keys()].filter((e, i, a) => myString.includes(myArray[e]));

console.log(res);

_{(You could also swap out e for i in the above function, but it's more understandable to do this because we're iterating through the keys.)}

edited Jul 11 '19 at 13:27

answered Jul 11 '19 at 13:09

Jack Bashford

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Or `.filter` for all – Jonas Wilms Jul 11 '19 at 13:09
Edited (a lot) @JonasWilms. – Jack Bashford Jul 11 '19 at 13:14
@JackBashford Your last example doesn't work? – Kobe Jul 11 '19 at 13:21
Fixed @Kobe - also thanks for the indices! – Jack Bashford Jul 11 '19 at 13:22
No worries, indexes sounds better but English is weird :P – Kobe Jul 11 '19 at 13:22
Indices is more mathematics-related. – Jack Bashford Jul 11 '19 at 13:24
@JackBashford in fact, you're correct. Indexes is actually the better plural to go for here, I never knew that was the rule. Index when pertaining to an indicator is perfectly fine as per [this](https://writingexplained.org/indexes-or-indices-difference). I never even knew indexes was a thing. You learn something new every day. – Kobe Jul 11 '19 at 13:26
No worries, I'll re-edit - thanks for fixing it anyway, I always appreciate people making me look smarter/less likely to have a trashy keyboard. – Jack Bashford Jul 11 '19 at 13:27

Find which array element exists in a string

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