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10-regular-expressions-javascript/12-regexp-anchors/article.md
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# String start ^ and finish $
The caret `pattern:'^'` and dollar `pattern:'$'` characters have special meaning in a regexp. They are called "anchors".
[cut]
The caret `pattern:^` matches at the end of the text, and the dollar `pattern:$` -- in the end.
For instance, let's test if the text starts with `Mary`:
```js run
let str1 = 'Mary had a little lamb, it's fleece was white as snow';
let str2 = 'Everywhere Mary went, the lamp was sure to go';
alert( /^Mary/.test(str1) ); // true
alert( /^Mary/.test(str2) ); // false
```
The pattern `pattern:^Mary` means: "the string start and then Mary".
Now let's test whether the text ends with an email.
To match an email, we can use a regexp `pattern:[-.\w]+@([\w-]+\.)+[\w-]{2,20}`. It's not perfect, but mostly works.
To test whether the string ends with the email, let's add `pattern:$` to the pattern:
```js run
let reg = /[-.\w]+@([\w-]+\.)+[\w-]{2,20}$/g;
let str1 = 'My email is mail@site.com';
let str2 = 'Everywhere Mary went, the lamp was sure to go';
alert( reg.test(str1) ); // true
alert( reg.test(str2) ); // false
```
We can use both anchors together to check whether the string exactly follows the pattern. That's often used for validation.
For instance we want to check that `str` is exactly a color in the form `#` plus 6 hex digits. The pattern for the color is `pattern:#[0-9a-f]{6}`.
To check that the *whole string* exactly matches it, we add `pattern:^...$`:
```js run
let str = "#abcdef";
alert( /^#[0-9a-f]{6}$/i.test(str) ); // true
```
The regexp engine looks for the text start, then the color, and then immediately the text end. Just what we need.
```smart header="Anchors have zero length"
Anchors just like `\b` are tests. They have zero-width.
In other words, they do not match a character, but rather force the regexp engine to check the condition (text start/end).
```
The behavior of anchors changes if there's a flag `pattern:m` (multiline mode). We'll explore it in the next chapter.