JavaScript - Replace all commas in a string

Question

I have a string with multiple commas, and the string replace method will only change the first one:

var mystring = "this,is,a,test"
mystring.replace(",","newchar", -1)

Result: "thisnewcharis,a,test"

The documentation indicates that the default replaces all, and that "-1" also indicates to replace all, but it is unsuccessful. Any thoughts?

Answer 1

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"