11th April 2021

# Multiline mode of anchors ^ \$, flag "m"

The multiline mode is enabled by the flag `m`.

It only affects the behavior of `^` and `\$`.

In the multiline mode they match not only at the beginning and the end of the string, but also at start/end of line.

## Searching at line start ^

In the example below the text has multiple lines. The pattern `/^\d/gm` takes a digit from the beginning of each line:

``````let str = `1st place: Winnie
2nd place: Piglet
3rd place: Eeyore`;

alert( str.match(/^\d/gm) ); // 1, 2, 3``````

Without the flag `m` only the first digit is matched:

``````let str = `1st place: Winnie
2nd place: Piglet
3rd place: Eeyore`;

That’s because by default a caret `^` only matches at the beginning of the text, and in the multiline mode – at the start of any line.

“Start of a line” formally means “immediately after a line break”: the test `^` in multiline mode matches at all positions preceded by a newline character `\n`.

And at the text start.

## Searching at line end \$

The dollar sign `\$` behaves similarly.

The regular expression `\d\$` finds the last digit in every line

``````let str = `Winnie: 1
Piglet: 2
Eeyore: 3`;

Without the flag `m`, the dollar `\$` would only match the end of the whole text, so only the very last digit would be found.

“End of a line” formally means “immediately before a line break”: the test `\$` in multiline mode matches at all positions succeeded by a newline character `\n`.

And at the text end.

## Searching for \n instead of ^ \$

To find a newline, we can use not only anchors `^` and `\$`, but also the newline character `\n`.

What’s the difference? Let’s see an example.

Here we search for `\d\n` instead of `\d\$`:

``````let str = `Winnie: 1
Piglet: 2
Eeyore: 3`;

As we can see, there are 2 matches instead of 3.

That’s because there’s no newline after `3` (there’s text end though, so it matches `\$`).

Another difference: now every match includes a newline character `\n`. Unlike the anchors `^` `\$`, that only test the condition (start/end of a line), `\n` is a character, so it becomes a part of the result.

So, a `\n` in the pattern is used when we need newline characters in the result, while anchors are used to find something at the beginning/end of a line.

Tutorial map

• To insert few words of code, use the `<code>` tag, for several lines – wrap them in `<pre>` tag, for more than 10 lines – use a sandbox (plnkr, jsbin, codepen…)