[javascript] JavaScript - Replace all commas in a string

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?

Just for fun:

var mystring = "this,is,a,test"  
var newchar = '|'
mystring = mystring.split(',').join(newchar);

var mystring = "this,is,a,test"
mystring.replace(/,/g, "newchar");

Use the global(g) flag

Simple DEMO