JavaScript 4 ways to judge whether a number and the efficiency of comparison _javascript skills

Today we have a comparison of the efficiency of chrome for different numerical methods, and the results are as follows:

Note: A regular expression can only be used to determine whether the content in a string is a pure numeric value and cannot be used to judge whether it is a numeric object. Put here for comparison purposes only.

The code is as follows:

 var ret;
 var o = 1;
 var pattern =/^ (-?\d*.? \d*) $/;
 var tostr = {}.tostring;
 var array = {};
 array["[Object number]"] = "number";
 
 Console.log ("All kinds of judging whether the speed of the numerical comparison!" ")
 
 Console.log (" Method one: Pattern.test (o) ");
 Console.time ("a");
 for (Var i=0;i<10000;i++) {
  ret = pattern.test (o);
 }
 Console.timeend ("a");
 Console.log (ret);

 Console.log ("Method two: 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 ("method Three: 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 ("Method four: 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);