javascript常用需求

生成随机数

 var native_random = Math.random;        Math.random = function(min, max, exact) {          if (arguments.length === 0) {            return native_random();          } else if (arguments.length === 1) {            max = min;            min = 0;          }          var range = min + (native_random()*(max - min));          return exact === void(0) ? Math.round(range) : range.toFixed(exact);        };        p(Math.random())        p(Math.random(10))        p(Math.random(3,10))        p(Math.random(2,10,4)) 

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