get charectors between two charectors in string
String.prototype.between = function(i1, i2) { var iA:String = this.indexOf(i1) + i1.length; if (i1 != i2 && this.indexOf(i1, iA) == -1) var iB:String = this.indexOf(i2, iA); else return this.substring(iA).between(i1, i2); return this.substring(iA, iB); };