factorial in javascript。不工作

Question

这里是剧本，我不明白为什么它不工作...

function FirstFactorial(num) { 

var lower = num - 1; 
var qq = 0; 

while (num > 0) { 
var qq === num * lower; 
num--; 
lower--; 
} 
num === qq; 
return num; 
} 
FirstFactorial(num); 

Answer 1

你有相当这个功能很少出现问题，请参阅评论。

function FirstFactorial(num) { 
    var lower = num - 1; 
    var qq = 0; 

    while (num > 0) { 
     // here you are shadowing the "qq" variable in the outer scope 
     // delete the "var" keyword to fix this 
     // also === is an identity operator, i think you wanted assignment (=) 
     // so this line becomes: qq = num * lower; 
     var qq === num * lower; 
     num--; 
     lower--; 
    } 

    // assuming that === was supposed to be = again 
    // you can rewrite this as just: return qq; 
    num === qq; 
    return num; 
} 

FirstFactorial(num); 

即使有了这些语法修正，您的逻辑计算阶乘是不正确的。编辑：工作例子（因为我很无聊）http://jsfiddle.net/gU2cz/

Answer 2

=是赋值运算符，===是全等运算符