javascript - 如何将一个函数的值传递给另一个函数？

Question

我正在学习 Javascript，我阅读了有关范围和变量的信息，但无法获得有关如何在函数之间发送变量的信息。请有人解释如何处理这种情况，最好推荐一些东西来阅读。

我想用 30 个不同的参数绘制一张图 30 次，并获取最后一个参数用于检查功能:

function loadImg{  
 .....
      img.onload = function() {   // Loading first picture at the start
        ........
           boo.onclick = function() {  // the function which by click start all process
               var i = 0;
               var num;  // the variable which I'm going to use for random numbers.
           setInterval(function() {      
               //   here I'm generating random numbers
                num = Math.floor(Math.random() * imgs.length);
            // and then start draw() function, which is going to get the 'num' parameter and draw a pictures with time interval ONLY 30 times
              if(i < 30){                    
              draw(num);
              i++; }, 2000);

            check(num); // after all, I want to run "check()" function which is going to get THE LAST from that 30 generated 'num' parameter and check some information. But is undefined, because it's outside the setInterval function and I don't wont to put it in, because it will starts again and again.

如何获取 check(num) 函数的最后一个参数？

附言抱歉我的英语不好，我一直在尽力描述 a。

Answer 1

您可以在 setInterval() 函数中调用 check(num) 条件:

if(i < 30){                    
  draw(num);
  i++;
}
else
{
   check(num);
}

然后您还应该结束循环，因为这将无限期地继续运行。

为此，将间隔分配给变量:

var myInterval = setInterval(function() { 

然后在调用check()之前清除间隔:

if(i < 30){                    
  draw(num);
  i++;
}
else
{
   clearInterval(myInterval);
   check(num);
}