done（）是否也可以在int上工作？

Question

I have this code in javascript (jquery)

function getTopLevelId(gender) {
            var catId = $.ajax({
            type: 'GET',
            url: '{url}'
            dataType: 'html'
        });

        return catId;   //Returns defered object    
    }

function getSelectedCategoryId() {
    return 7; //returns int based on value in an element
};


function mainFuncion(id) {
    if (parseInt(id) === 0) {
        catObj= getTopLevelId(gender);    //Returns defered object       
    }
    else {
        catId = getSelectedCategoryId(id);  //Returns int
        catObj = catId;
    }

    $.when(catObj).done(function(catId) {
            //Doing some stuff and want to use catId as a category id
    }
}

My question is about "Doing some stuff" in done(). It SEEMS to me like done() is called and giving me correct category id even if catId is just an int, but is this always true? Or is there any other way that might be "safer" to achieve what I want in mainFunction?

Answer 1

Yes. If none of the params passed to $.when() are unresolved promise objects then the done handler is called immediately.

If a single argument is passed to jQuery.when and it is not a Deferred or a Promise, it will be treated as a resolved Deferred and any doneCallbacks attached will be executed immediately. The doneCallbacks are passed the original argument. In this case any failCallbacks you might set are never called since the Deferred is never rejected.

var a = 7;
$.when(a).done(function (x) {
    console.log('inside', x)
});
console.log('after')

Demo: Fiddle , Fiddle2