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Chris Bongers
Chris Bongers

Posted on • Originally published at daily-dev-tips.com

JavaScript startsWith and multiple conditions

You might have heard of the JavaScript startsWith method. It can check if a particular string starts with another string.

To give you a demonstration it would work something like this:

const string = 'Hi, and welcome from JavaScript';
console.log(string.startsWith('Hi'));
// true
console.log(string.startsWith('Hello'));
// false
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Checking for multiple conditions with startsWith

But what if we want to check if a string starts with a multiplication of strings?

So let's say Hi and Hello would both be fine.

We could use a conditional statement. However, this might get very unorganized if we decide to allow more strings at a later stage.

However, it would look like this:

const string = 'Hi, and welcome from JavaScript';
const result = string.startsWith('Hi') || string.startsWith('Hello');
console.log(result);
// true
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Another way is to use the same method on a predefined array. I quite like the simplicity and naming of this method as it really states what's happening.

This is what it looks like:

const result = ['Hi', 'Hello'].some(word => string.startsWith(word));
console.log(result);
// true
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Feel free to try these out in the following CodePen.

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Discussion (4)

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Alex Lohr

You can also directly use a bound method, i.e.

const result2 = ["Hi", "Hello"].some(string.startsWith.bind(string));
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Chris Bongers Author

Oh nice one! πŸŽ‰

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xahin289 profile image
Jannatun Nayeem

Really a helpful post. Tottally understand the logic, Thank you very much.

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Chris Bongers Author

Thanks Jannatun!
Glad it's clear πŸ‘