29 lines
814 B
Markdown
29 lines
814 B
Markdown
---
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title: String starts with substring
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shortTitle: Starts with substring
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tags: string
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cover: boutique-home-office-3
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author: chalarangelo
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firstSeen: 2022-07-31T05:00:00-04:00
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---
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Checks if a given string starts with a substring of another string.
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- Use a `for...in` loop and `String.prototype.slice()` to get each substring of the given `word`, starting at the beginning.
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- Use `String.prototype.startsWith()` to check the current substring against the `text`.
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- Return the matching substring, if found. Otherwise, return `undefined`.
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```js
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const startsWithSubstring = (text, word) => {
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for (let i in word) {
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const substr = word.slice(-i - 1);
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if (text.startsWith(substr)) return substr;
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}
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return undefined;
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};
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```
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```js
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startsWithSubstring('/>Lorem ipsum dolor sit amet', '<br />'); // '/>'
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```
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