The third parameter of String.prototype.replace() function was never defined as a standard, so most browsers simply do not implement it.
The best way is to use regular expression with g (global) flag.
var myStr = 'this,is,a,test';
var newStr = myStr.replace(/,/g, '-');
console.log( newStr ); // "this-is-a-test"
Still have issues?
It is important to note, that regular expressions use special characters that need to be escaped. As an example, if you need to escape a dot (.) character, you should use /\./ literal, as in the regex syntax a dot matches any single character (except line terminators).
var myStr = 'this.is.a.test';
var newStr = myStr.replace(/\./g, '-');
console.log( newStr ); // "this-is-a-test"
If you need to pass a variable as a replacement string, instead of using regex literal you may create RegExp object and pass a string as the first argument of the constructor. The normal string escape rules (preceding special characters with \ when included in a string) will be necessary.
var myStr = 'this.is.a.test';
var reStr = '\\.';
var newStr = myStr.replace(new RegExp(reStr, 'g'), '-');
console.log( newStr ); // "this-is-a-test"
