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| 1 | +--- |
| 2 | +Title: '.match()' |
| 3 | +Description: 'Returns an array of matches by matching the string against a regular expression.' |
| 4 | +Subjects: |
| 5 | + - 'Computer Science' |
| 6 | + - 'Web Development' |
| 7 | +Tags: |
| 8 | + - 'Arrays' |
| 9 | + - 'Methods' |
| 10 | + - 'Strings' |
| 11 | +CatalogContent: |
| 12 | + - 'introduction-to-javascript' |
| 13 | + - 'paths/front-end-engineer-career-path' |
| 14 | +--- |
| 15 | + |
| 16 | +The **`.match()`** method searches a string for matches against a regular expression and returns the result as an array object. The `.match()` method is used in JavaScript to find parts of a string that match a regular expression. It is commonly applied in tasks such as extracting numbers or words, validating formats like email addresses, or parsing structured text. |
| 17 | + |
| 18 | +## Syntax |
| 19 | + |
| 20 | +```pseudo |
| 21 | +string.match(regex) |
| 22 | +``` |
| 23 | + |
| 24 | +**Parameters:** |
| 25 | + |
| 26 | +- `regex`: A regular expression object to match against the string. |
| 27 | + |
| 28 | +**Return value:** |
| 29 | + |
| 30 | +- **If the regular expression has the `g` flag:** Returns an array of all matches found, or `null` if no match is found. |
| 31 | +- **Without the `g` flag:** Returns an array with detailed information about the first match (including captured groups), or `null` if no match is found. |
| 32 | + |
| 33 | +## Example 1: Using `.match()` to Find Uppercase Letters in a String |
| 34 | + |
| 35 | +In the following example, a string variable `paragraph` contains a sentence, and `regex` defines a regular expression to match all uppercase letters. The `.match()` method applies this regex to the string and returns an array of all matches: |
| 36 | + |
| 37 | +```js |
| 38 | +const paragraph = 'The quick brown fox jumps over the lazy dog. It barked.'; |
| 39 | +const regex = /[A-Z]/g; |
| 40 | +console.log(paragraph.match(regex)); |
| 41 | +``` |
| 42 | + |
| 43 | +The output of this code will be: |
| 44 | + |
| 45 | +```shell |
| 46 | +[ 'T', 'I' ] |
| 47 | +``` |
| 48 | + |
| 49 | +If the "g" flag is not used, it returns the array object with the result at index 0: |
| 50 | + |
| 51 | +```js |
| 52 | +const paragraph = 'The quick brown fox jumps over the lazy dog. It barked.'; |
| 53 | +const regex = /[A-Z]/; |
| 54 | +console.log(paragraph.match(regex)); |
| 55 | +``` |
| 56 | + |
| 57 | +The output of this code will be: |
| 58 | + |
| 59 | +```shell |
| 60 | +[ |
| 61 | + 'T', |
| 62 | + index: 0, |
| 63 | + input: 'The quick brown fox jumps over the lazy dog. It barked.', |
| 64 | + groups: undefined |
| 65 | +] |
| 66 | +``` |
| 67 | + |
| 68 | +## Example 2: Finding All Occurrences of a Word Using `.match()` |
| 69 | + |
| 70 | +This example demonstrates how to use the `.match()` method to find all occurrences of the word "Hello" in a string: |
| 71 | + |
| 72 | +```codebyte/javascript |
| 73 | +const myStr = 'Hello Alligators, Hello Devs, how are you?'; |
| 74 | +const regex = /Hello/g; |
| 75 | +console.log(myStr.match(regex)) |
| 76 | +``` |
| 77 | + |
| 78 | +The output of this code is: |
| 79 | + |
| 80 | +```shell |
| 81 | +[ 'Hello', 'Hello' ] |
| 82 | +``` |
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