How to replace an apostrophe in a string in Javascript?-Collection of common programming errors

var str = "this's kelly"
str = str.replace(/'/g, 'A');

The reason your version wasn’t working is because str.replace returns the new string, without updating in place.

I’ve also updated it to use the regular expression version of str.replace, which when combined with the g option replaces all instances, not just the first. If you actually wanted it to just replace the first, either remove the g or do str = str.replace("'", 'A');