JavaScript判断是否为数字的4种方法及效率比较

 var ret;
 var o = 1;
 var pattern = /^(-?\d*.?\d*)$/;
 var toStr = {}.toString;
 var array = {};
 array["[object Number]"] = "number";
 
 console.log("各种判断是否数值的速度比较！")
 
 console.log("方法一：pattern.test(o)");
 console.time("first");
 for (var i=0;i<10000;i++){
  ret = pattern.test(o);
 }
 console.timeEnd("first");
 console.log(ret);

 console.log("方法二：o instanceof Number");
 console.time("second");
 for (var i=0;i<10000;i++){
  ret = o instanceof Number;
 }
 console.timeEnd("second");
 console.log(ret);
 
 console.log("方法三：o.constructor == Number");
 console.time("thirth");
 for (var i=0;i<10000;i++){
  ret = o.constructor == Array;
 }
 console.timeEnd("thirth");
 console.log(ret);

 console.log("方法四：array[toStr.call(o)] == 'number'");
 console.time("forth");
 for (var i=0;i<10000;i++){
  ret = array[toStr.call(o)] == "number";
 }
 console.timeEnd("forth");
 console.log(ret);