输入框输入值自动格式化,每4位加空格或-

<h3>这里设置第四位开始加空格</h3><input data-gap=4 maxlength="14" size="14"    autocomplete="on" type="text" placeholder="请输入卡号"/><button>获取输入值</button><script>var input = document.querySelectorAll('input')[0];var gap = parseInt(input.getAttribute('data-gap'));input.oninput = function() {  var numbers = this.value.replace(/[^\w]|/ig, '').split('')  ;   // 获取原始值//  var numbers = this.value.replace(/\s+/g, '').split('')     // 获取原始值  var back = '' ;  numbers.forEach(function(n, i) {    back += n + ((i + 1) % gap === 0 ? '-' : '') ;   // 处理加空格或-  });  var len = back.length;  var last = back.charAt(len - 1);   //if (last === ' ' || isNaN(last)) {  if (last === ' ' || last === '-') {    back = back.substring(0, len - 1) ;   // 移除末尾无用字符  }  this.value = back.toUpperCase();  // 兼容处理  setTimeout(function() {    this.setSelectionRange(len, len);    this.focus();  }.bind(this), 0);};</script>