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Quick JavaScript Tip: the some() method

Matt Sparks on May 22, 2019

I recently learned of a great JavaScript method I'd never used. It was brought to my attention by Wes Bos. The some() method is a convenient way to...

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Atta • May 22 '19 • Edited

I think .includes() is better than .some() for checking if an array contains a value or not:

const animals = ['dogs', 'cats', 'snakes', 'birds', 'pandas'];
animals.includes('snakes'); // true

.some() is good for other use-cases like finding if a value > 15 exists in an array:

[2, 15, 18, 5, 4].some(x => x > 15);  // true

Matt Sparks • May 22 '19

I agree, .includes() would be a better solution for the specific problem I laid out. I just wanted to give a simple bit of code to illustrate how .some() works.

I'll try and add a second example to show another use-case.

Thanks!

Steven Washington • May 22 '19

I was thinking the same string, but some reminds me of a function I wrote a long time ago (in PHP) called someValidStrings which checked an array to make sure that there was at least 1 value that was correctly typed as a String, and also fulfilled some other business logic on what was considered "valid" (think: string length, ends with a run of 3 numbers, etc.). This is a case that some would excel at with the function callback rather than just looking for a certain value.

I was thinking that I could use find for the same purpose, but I see that there's a logical benefit to returning a boolean directly rather than a value that would have to be checked. I imagine find, some and findIndex work very similarly and only really differ in what they return.

Jecsham • May 22 '19

Nice post!

A strange example 😅:

// check for types! in this case, check if your array has a number
["str", "str2", {key: 3}, 5].some(x => typeof x === "number"); // true
["str", "str2", {key: 3}, "5"].some(x => typeof x === "number"); // false

Logan Mitchell • May 23 '19 • Edited

It is quite handy!

I used .some() coupled with .includes() a while back to cross-reference two string arrays to make sure the user had at least one of the required roles for an action. The benefit of .some() here is that it will return true no matter how many of the iterations are false, as long as one of them is true.

//sample data
let userRoles = ['a','b','c','d'];
let validRoles = ['c','d','e','f'];
//end sample data

private isRoleValid(userRoles: string[], validRoles: string[]) {
    return userRoles && userRoles.some(e => validRoles.includes(e));
}