一段时间后自动调用Javascript函数的正确方法是什么？

Question

I need to call a function after one minute and update the div .

Basically I need to refresh the page as the new entry comes in the table, so what I think is to Ajax call and update the content after one minute. Please tell me whether this is right approach?

Answer 1

If you need the function to run every 60 seconds, you can use setInterval() :

setInterval(function() {
    /* AJAX call here. */
}, 60000);

If you only need it to run only once, you can use setTimeout() :

setTimeout(function() {
    /* AJAX call here. */
}, 60000);

For both, 60,000 is the millisecond delay (60,000ms = 1 minute).

Answer 2

Instead of using a setInterval you could execute a setTimeout of 60 seconds (60000 ms) to the function that makes the ajax call only if the previous call has been successfully completed (so, as example, you can avoid to make useless ajax calls if your server return a 404 or a 500 status for a given resource)

var xhr = new XMLHttpRequest();

function doAjaxCall() {
    ...
    xhr.onReadyStateChange = function() {

        ...
        if (xhr.readyState === 4) {
            if (xhr.status === 200 || xhr.status === 304) { 
                setTimeout(doAjaxCall, 60000);
            }
        }
    }
}

doAjaxCall();

Answer 3

setTimeout() and it's brother setInterval()

setTimeout - calls once

setInterval - calls every specified interval

Examples:

setTimeout(function() { doStuffOnce(); }, 1000);
setInterval(function() { doStuff(); }, 1000);

Answer 4

If all you need to do is wait for the AJAX to complete, then you shouldn't use a fixed timeout. What happens if the AJAX call takes more than one minute? And why make users wait for a whole minute (which is forever in a browser) if the AJAX call completes (as is typical) in a second or so. Instead, simply use the callback of the AJAX call itself, eg

$("/url/to/your/AJAX").done(function(data) {
  // do what you need to do with the data now
})

Answer 5

Youy can use both The setTimeout() method calls a function or evaluates an expression after a specified number of milliseconds.

setTimeout(code,millisec,lang)

code Required. The function that will be executed millisec Required. The number of milliseconds to wait before executing the code lang Optional. The scripting language: JScript | VBScript | JavaScript

The setInterval() method calls a function or evaluates an expression at specified intervals (in milliseconds).

The setInterval() method will continue calling the function until clearInterval() is called, or the window is closed.

The ID value returned by setInterval() is used as the parameter for the clearInterval() method.

Tip: 1000 ms = 1 second.

setInterval(code,millisec,lang)

code Required. The function that will be executed millisec Required. The intervals (in milliseconds) on how often to execute the code lang Optional. JScript | VBScript | JavaScript