settimeout javascript无法正常运行？

Question

I am using the following code in order to display some texts to the users.

basically what I need to show is:

1 2 3 4

but this code shows,

1 4

here is the code:

    <script>
    function myFunction() {
    setTimeout(function() {
      document.getElementById('p').innerHTML = "1";
    }, 2000);

    setTimeout(function() {
      document.getElementById('p').innerHTML = "2";
    }, 4000);

    setTimeout(function() {
      document.getElementById('p').innerHTML = "3";
    }, 4000);

    setTimeout(function() {
      document.getElementById('p').innerHTML = "4";
    }, 4000);
    };
    </script>


<p id="p"></p>

<input onclick="myFunction()" type="submit" />

does anyone know why this is happening?

Thanks in advance.

Answer 1

because

setTimeout(function() {
  document.getElementById('p').innerHTML = "2";
}, 4000);

setTimeout(function() {
  document.getElementById('p').innerHTML = "3";
}, 4000);

setTimeout(function() {
  document.getElementById('p').innerHTML = "4";
}, 4000);
};

are editing the same element so you see only the result of the last operation: 4

---

The setTimeout() method calls a function or evaluates an expression after a specified number of milliseconds. and in your case the time is same, so all executed at same time.

set some interval between them.

Answer 2

setTimeout doesn't calculate time from the finishing of previous setTimeout , but from the time the setTimeout statement was executed.

So, all the setTimeout statements with 2 , 3 and 4 are beginning to wait 4 seconds almost at the same time.

Answer 3

您正在快速连续地编辑相同的元素，如果您为setTimeout设置了不同的值，例如1000、2000、3000、4000，您会看到文本从1更改为2到3更改为4，间隔为1s（大约）每次更改。