Replace over multiple lines with javascript replace()

Question

I need some help with replacing multiple lines in a javascript. I have read something about using flags, but I dont know how to implement them.

This is my current replace()

var res = str.replace(selectedText,'<b>' + selectedText + '</b>');

It is working for a single line, but not for multiple lines.

If selectedText was:

aaa bbb

ccc

The result would be:

aaa bbb

ccc

Any tips?

//Ambrose

Answer 1

If you give replace a string for the first argument, only the first match is replaced. To replace all matches, you have to pass in an regular expression as the first argument, and use the g flag on it. This replaces all as with bs:

var str = "a a a a";
str = str.replace(/a/g, 'b');
console.log(str); // "b b b b"

So you'll need to create a regular expression for selectedText. You can do that via new RegExp(selectedText, "g"):

var res = str.replace(new RegExp(selectedText, "g"),'<b>' + selectedText + '</b>');

...but if selectedText has any characters in it that have special meaning in a regular expression, you have to escape those. Sadly, JavaScript has no built-in function for doing that, but if you search around you can find several examples of functions to do it. This answer on SO has some options as well.

If we use the RegExp.escape from this answer to that question (it's a bit overkill, but fairly harmless in its overkill-ness):

RegExp.escape= function(s) {
    return s.replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&');
};

...then:

var res = str.replace(new RegExp(RegExp.escape(selectedText), "g"),'<b>' + selectedText + '</b>');