Replace first character of string

You can do exactly what you have :)

var string = "|0|0|0|0";
var newString = string.replace('|','');
alert(newString); // 0|0|0|0

You can see it working here, .replace() in javascript only replaces the first occurrence by default (without /g), so this works to your advantage :)

If you need to check if the first character is a pipe:

var string = "|0|0|0|0";
var newString = string.indexOf('|') == 0 ? string.substring(1) : string;
alert(newString); // 0|0|0|0​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​

You can see the result here

var newstring = oldstring.substring(1);

str.replace(/^\|/, "");

This will remove the first character if it's a |.