how to replace last occurrence of a word in javascript?

Question

for example:

var str=\"
hi
hi\";

to replace the last(second)
,

to change into \"<

Answer 1

You can use the fact that quantifiers are greedy:

str.replace(/(.*)<br>/, "$1");

But the disadvantage is that it will cause backtracking.

Another solution would be to split up the string, put the last two elements together and then join the parts:

var parts = str.split("<br>");
if (parts.length > 1) {
    parts[parts.length - 2] += parts.pop();
}
str = parts.join("<br>");

Answer 2

I think you want this:

str.replace(/^(.*)<br>(.*?)$/, '$1$2')

This greedily matches everything from the start to a <br>, then a <br>, then ungreedily matches everything to the end.

Answer 3

String.prototype.replaceLast = function(what, replacement) { 
    return this.replace(new RegExp('^(.*)' + what + '(.*?)$'), '$1' + replacement + '$2');
}

str = str.replaceLast(what, replacement);