JQuery GetJSON inside SetTimeOut Timer

问题:

Can anyone post a sample code wherein theres a running timer(javascript settimeout) and doing data retrieval..

basically what i this timer does is to display new messages..

myFunction(param){

//data retrieval operation
//using getJSON.. call displaydata() base on param

settimeout("myFunction()", param, 1000);

}

function displaydata(param){

//processing
alert('test')}

Should i use getJSON? i think theres a problem with the asynchronous call..

回答1:

Two things I noticed you need to fix in your code.

• The setTimeout() method has some incorrect arguments
• Your asynchronous getJSON call creates a race condition between the next timeout and the result of the getJSON method. Do this instead:

.

function yourFunction(params) {  
    jQuery.getJSON("url", {data}, function(data, textStatus){
        // handle your JSON results

        // Call the timeout at the end of the AJAX response
        // This prevents your race condition
        setTimeout(function(){
            yourFunction(params);
        }, 1000);
    }
} 

setTimeout(function(){
    yourFunction(params);
}, 1000);

回答2:

The first parameter should be a function literal or a function reference and the second parameter should be the milliseconds.

setTimeout( function() {
    getData('param')
}, 1000);

function getData() {
     $.getJSON("http://api.flickr.com/services/feeds/photos_public.gne?tags=cat&tagmode=any&format=json&jsoncallback=?",
        function(data){
          $.each(data.items, function(i,item){
            $("<img/>").attr("src", item.media.m).appendTo("body");
            if ( i == 3 ) return false;
          });
        });
}

I'm not using the actual argument in my example but you can easily update it to do so. Also I wasn't sure if you were polling ( this doesn't do poll/recursive calling ).