How to count the number of lines of a string in javascript

Using a regular expression you can count the number of lines as

 str.split(/\r\n|\r|\n/).length

Alternately you can try split method as below.

var lines = $("#ptest").val().split("\n");  alert(lines.length);

javascript string split

Another short, potentially more performant than split, solution is:

const lines = (str.match(/\n/g) || '').length + 1

javascript string split

To split using a regex use /.../

lines = str.split(/\r\n|\r|\n/);

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