I thought that this would add a space after each 4 chars, but instead, after the fourth digit the input is set to ''. Why?
keyUp: function(e) {
if (e.target.value.length === 4) {
var value = e.target.value + ' ';
e.target.value = value;
}
else if (e.target.value.length === 9) {
e.target.value += ' ';
}
else if (e.target.value.length === 14) {
e.target.value += ' ';
}
},