Filter list of array with regex

Question

I'm trying to filter this

Alert me when this account’s current balance goes above $1.

from the list here:

alertTypes = [
 'Alert me when this account’s available balance goes below $1.',
 'Alert me when this account’s current balance goes below $1.',
 'Alert me when this account’s available balance goes above $1.',
 'Alert me when this account’s current balance goes above $1.']

Using this async function

const alertRegEx = "/.*current balance.*above.*/"
const alert = alertTypes.filter(alert => alert.match(alertRegEx))

But im getting the whole list in alert variable. What's my mistake here?

You regex is not a regex but a string. Try removing the quotes — StackByMe
– StackByMe, Commented Sep 16, 2021 at 7:19
Also, why use async/await? There is no asynchronous code here. Moreover, you cannot use an async function for a .filter() predicate. — VLAZ
– VLAZ, Commented Sep 16, 2021 at 7:20
I just did a shortcut but basically the regex came from a json. say something like { "test" : { "testRegex": "/.*current balance.*above.*/"} } — Octane
– Octane, Commented Sep 16, 2021 at 7:25

Gabriele Petrioli · Accepted Answer · 2021-09-16 07:24:20Z

2

Firstly, do not use async in this case as match is not an async function (but even if it was you would not be able to use it in a filter). Then you need to use an literal regular expression,not a string.

And a minor, non-required, change is that you can skip the initial and final .*

const alertTypes = [
 'Alert me when this account’s available balance goes below $1.',
 'Alert me when this account’s current balance goes below $1.',
 'Alert me when this account’s available balance goes above $1.',
 'Alert me when this account’s current balance goes above $1.']



const alertRegEx = /current balance.*above/;
const alerts = alertTypes.filter( alert =>  alert.match(alertRegEx))

console.log(alerts);

edited Sep 16, 2021 at 7:24

answered Sep 16, 2021 at 7:21

Gabriele Petrioli

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3 Comments

Octane Over a year ago

I just clipped this but basically the regex came from a json file. So I had to add the quotes.

Gabriele Petrioli Over a year ago

Then you could create a regular expression out of it by using const actualRegex = new RegExp(alertRegEx); but you will need to remove the starting & ending /

Octane Over a year ago

I will try this. Do I still use the filter function? or the .test now?

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