Question

var count = 0; 

function goFast(){
    ++count;
    console.log("Go straight and then ");
    var direction = "right"; if (count%2===0){direction="left";}
    turn(direction);
    console.log("Thank you passenger #" + count);
}

var turn = function(direction) {
    console.log("turn to your " + direction)
}

goFast();
goFast();

goFast功能负责计算有多少旅行者通过，并询问他们应该转向的另一个功能（可选择向左或向右注销）。

如何将我的count变量放在goFast函数中，从而更好地封装它，但是每次调用函数时都不重新初始化它？

这是一个jsfiddle：http://jsfiddle.net/legolandbridge/sU8T8/

Answer 1

一种方法是将其包装在闭包中并返回一个可以访问count变量的函数。例如，

var goFast = (function() {
    var count = 0;
    return function() {
        ++count;
        console.log("Go straight and then ");
        var direction = "right"; if (count%2===0){direction="left";}
        turn(direction);
        console.log("Thank you passenger #" + count);
    };
})();

Answer 2

将其定义包含在另一个函数中以创建临时范围。

var goFast = (function() { 
   var count = 0;
   return function() {
       ++count;
       console.log("Go straight and then ");
       var direction = "right"; if (count%2===0){direction="left";}
       turn(direction);
       console.log("Thank you passenger #" + count);
   };
})();

Answer 3

你可以做这样的事情，但它不是最漂亮的，因为turn不在goFast()之内..是的，没有看到好处。：

function goFast(){
    if ( !window.count )
            window.count = 0;
    ++count;
    console.log("Go straight and then ");
    var direction = "right"; if (count%2===0){direction="left";}
    turn(direction);
    console.log("Thank you passenger #" + count);
}

var turn = function(direction) {
    console.log("turn to your " + direction)
}

goFast();
goFast();

http://jsfiddle.net/daCrosby/sU8T8/1/

如何将我的计数器变量放在其功能范围内？

3 个答案: