javascript masking if input matches patter
document.getElementById("phone").addEventListener("keyup", function(){
// restart the match
this.value = this.value.replace(/\s/g, "");
// Assess the amount needed
var v = this.value.match(/(\d)(\d{1,3})?(\d{1,2})?(\d+)?/);
if(v){
// Save the desired value depending on its existence
v = (v[1]?v[1]+(v[2]?" "+v[2]+(v[3]?" "+v[3]+(v[4]?" "+v[4]:""):""):""):"");
// and yea!
this.value = v;
}
});