如何在 while 循环中添加延迟。 JavaScript

Question

        function falling()
        {
            isFalling = true;

            while (isFalling == true)
            {

                if (y < 120) {

                    y++;

                }
                else if (y == 120) {
                    isFalling = false;

                }

            }

        }

I have tried adding setTimeout(function() around the entire loop, around the if statement, around the y++. I don't know what i'm doing wrong. Any time I add any of these the page becomes unresponsive once the falling function is called. I'm well aware that this is probably a duplicate question but the duplicate questions failed ti help. { }, 100)

Answer 1

You would do it like this:

function falling(y) {
    if (y < 120) {
        setTimeout(falling.bind(this, y + 1), 100); // specify your delay.
    }
}

falling(0);

The question has indeed been answered several times, and the answers here are really not that different from this.

Note that I removed the apparently global variable isFalling . If you do need that variable in other code, then you can keep that variable updated as follows:

function falling(y) {
    isFalling = y < 120;
    if (isFalling) {
        setTimeout(falling.bind(this, y + 1), 100); // specify your delay.
    }
}

Answer 2

I would use window.setInterval() instead, as you want it to repeat until a certain number

working plunkr:

https://plnkr.co/edit/TbpplnIShiaJR7sHDUjP?p=preview

function falling()
    {
        var isFalling = true; 
        var y=0;
        myInterval = window.setInterval(function() {
          y++;
          console.log(y);
          if (y== 120) {
            clearInterval(myInterval);
          }
        }, 100)
    }

falling();

Answer 3

If the intent of calling falling() is to temporarily set the value of a global variable to true (as suggested by your current code), then this should do the trick.

 var isFalling = false; function falling(fallDuration) { isFalling = true; console.log("now falling"); setTimeout(function(){ isFalling = false; console.log("landed"); }, fallDuration || 1000); } falling();

I imagine though that you might actually want to fall and then continue doing something else. In that case you probably want to look at a callback or into promises. You might do a simple:

 var isFalling = false; function falling(fallDuration, andThen) { isFalling = true; console.log("now falling"); setTimeout(function() { isFalling = false; console.log("landed"); andThen(); }, fallDuration); } falling(1000, function(){ console.log("now standing"); });