jquery numerical input box implementation

This js is introduced on the page, and the text keyup and blur events are monitored. Refer to the text written by easyui. No numerical verification is done when the text box is initialized. Those who are interested can refer to the following blur event to achieve

 

<input type="text" class="ll-numberbox" data-options="min:0.1,max:999,precision:2" value="" />

 

//数值输入框格式化
String.prototype.endWith = function(str) {
  if (str == null || str == "" || this.length == 0 || str.length > this.length)
    return false;
  if (this.substring(this.length - str.length) == str)
    return true;
  else
    return false;
  return true;
}
String.prototype.startWith = function(str) {
  if (str == null || str == "" || this.length == 0 || str.length > this.length)
    return false;
  if (this.substr(0, str.length) == str)
    return true;
  else
    return false;
  return true;
}
String.prototype.trim = function() {
  return this.replace(/(^\s*)|(\s*$)/g, '');
};
$(function() {
  $("body").on("keyup", ".ll-numberbox", function(e) {
    if(e.which == 8 || e.which == 0 || (e.which >= 48 && e.which <= 57 && e.ctrlKey == false && e.shiftKey == false)) {
      return false;
    }
    var t_v = $(this).val().trim().replace(/[^\d\.\-]/g, '');
    $(this).val(t_v);
  })
  
  $("body").on("blur", ".ll-numberbox", function(e) {
    var options = $(this).attr("data-options").split(",");
    var t_v = $(this).val().trim().replace(/[^\d\.\-]/g, '');
    if (t_v == '') {
      $(this).val(t_v);
      return false;
    }
    
    if(t_v.startWith(".")) {
      t_v = "0" + t_v;
    }

    var a1, a2;
    var sp = t_v.split(".");
    if (sp.length >= 2) {
      a1 = sp[0];
      a2 = sp[1];
    } else {
      a1 = sp[0];
      a2 = '00';
    }
    t_v = a1 + "." + a2;

    var min, max, precision = 0;// 最小值，最大值，小数位

    for (var i = 0; i < options.length; i++) {
      if (options[i].startWith("min:"))
        min = options[i].replace("min:", "");
      if (options[i].startWith("max:"))
        max = options[i].replace("max:", "");
      if (options[i].startWith("precision:"))
        precision = parseInt(options[i].replace("precision:", ""));
    }
    if (parseFloat(t_v) - parseFloat(min) < 0) {
      t_v = min;
    }
    if (parseFloat(t_v) - parseFloat(max) > 0) {
      t_v = max;
    }

    t_v = parseFloat(t_v).toFixed(precision)
    $(this).val(t_v);
  })
})