How to replace all characters in a string using JavaScript for this specific case: replace . by _

Question

The following statement in JavaScript works as expected:

var s1 = s2.replace(/ /gi, '_'); //replace all spaces by the character _

However, to replace all occurrences of the character . by the character _, I have:

var s1 = s2.replace(/./gi, '_');

But the result is a string entirely filled with the character _

Why and how to replace . by _ using JavaScript?

Answer 1

The . character in a regex will match everything. You need to escape it, since you want a literal period character:

var s1 = s2.replace(/\./gi, '_');

Answer 2

you need to escape the dot, since it's a special character in regex

s2.replace(/\./g, '_');

Note that dot doesn't require escaping in character classes, therefore if you wanted to replace dots and spaces with underscores in one go, you could do:

s2.replace(/[. ]/g, '_');

Using i flag is irrelevant here, as well as in your first regex.

Answer 3

You can also use strings instead of regular expressions.

var s1 = s2.replace ('.', '_', 'gi')

Answer 4

There is also this that works well too :

var s1 = s2.split(".").join("_"); // Replace . by _ //