jQuery setTimeout如果不使用警报将无法正常工作

Question

I am implementing this code.

$('.mcqtd').click(function(){
var choice = this.id;   
    checkanswer(choice,questions[x].correctAnswer);
    window.setTimeout(showquestion(x+1,0),3000); // 1 seconds
});

}

function checkanswer(answer,original){
    if (answer=='choice'+original){
        $('#choice'+original).css('backgroundColor', '#DD792E');
        $('#choice'+original).append("<span class='padding10 mcqsymbol'><img src='images/right_icon.png' /></span>");
    } else {
        $('#'+answer).css('backgroundColor', '#AFA689');
        $('#'+answer).append("<span class='padding10 mcqsymbol'><img src='images/wrong_icon.png' /></span>");
        $('#choice'+original).css('backgroundColor', '#DD792E');
        $('#choice'+original).append("<span class='padding10 mcqsymbol'><img src='images/right_icon.png' /></span>");
    }
}

Onclick , the tds should be highlighted, and after 3 seconds, the next question should be loaded but this is not happening, after 3 seconds the next question is being loaded, but backgrounds are not changing. If I alert something inside checkanswer() , the code works. Any ideas what should I do?

Answer 1

The to executing part must be wrapped in a anonymous function if you want to use parametes. Otherwise it is not working in setTimeout .

setTimeout(function() {
    showquestion(x + 1, 0);
}, 3000);

As A.Wolff noted in the comments below, you can even pass parameters to a called function in setTimeout by extening the parameters behind the time.

// note there are no '()' behind the function name
setTimeout(showquestion, 3000, x + 1, 0);

If you would call a function without parameters you can left out the wrapper function and the additional parameters too.

// note there are no '()' behind the function name
setTimeout(functionWithoutParameter, 3000);

Answer 2

What you do is calling the function directly and passing it's return value over to setTimeout . As you intend to use arguments with this, you will have to make use of an anonymous function , eg:

setTimeout(function(){ showquestion(x+1, 0);}, 3000);

Edit:

If you only have a functioncall without arguments it woulf look like:

setTimeout("foo()", 3000);

or

setTimeout(foo, 3000);

Answer 3

Dirtly call this in setTimeout method its not working.

  setTimeout(question, 3000);

   function question() {
     showquestion(x + 1, 0)
   }