蝴蝶不菲
var variance = function(numbers) {var mean = 0;var sum = 0;for(var i=0;i<numbers.length;i++){sum += numbers[i];}mean = sum / numbers.length;sum = 0;for(var i=0;i<numbers.length;i++){sum += Math.pow(numbers[i] - mean , 2);}return sum / numbers.length;};