Question

我有一个横幅旋转器，我想使用对象而不是函数，所以我可以使代码更有效。无论如何，我似乎无法让setInterval工作。我认为它与对象引用有关。任何人都能解释一下吗？这是我到目前为止所得到的：

window.addEvent('domready', function() {
function set_banner(divid, array)
{
    var banner = $(divid);
    banner.set('html', '<a href=""><img src="" alt=""/></a>');
    var banner_link = $(divid).getElement('a');
    var banner_image = $(divid).getElement('img');

    var delay = 0;  

    for (var keys in banner1array) {
        var callback = (function(key) { return function() {
            banner.setStyle('opacity', 0);
            var object = array[key];
            for (var property in object) {
                if (property == 'href') {
                    var href = object[property];
                }
                if (property == 'src') {
                    var src = object[property];
                }
            }
            if (!banner.getStyle('opacity')) {
                banner.set('tween', {duration:1000});                   
                banner_link.setProperty('href', href);
                banner_image.setProperty('src', src);
                banner.tween('opacity', 1);
            }
        }; })(keys);
        setTimeout(callback, delay);
        delay += 21000;
    }
}

var banner1 = set_banner('banner1', banner1array);
setInterval(function() {set_banner('banner1', banner1array);}, 84000);

var banner2 = set_banner('banner2', banner2array);
setInterval(function() {set_banner('banner2', banner2array);}, 84000);

}）;

Answer 1

一个简单的错误：

 var banner1 = new set_banner('banner1');
               ^ ---------- creates a new object and uses set_banner as the constructor
                            your code already gets called here
                            and you get a new object back, which in this case has NO use

 ....
 setInterval(banner1(), 42000);
                     ^----------------- The parenthesis EXECUTE the function
                                        the RETURN VALUE is then passed to setInterval
                                        BUT... banner1() is NOT a function, so this fails

如果您想在42秒后调用set_banner并传递参数，您想要做的是使用匿名函数然后调用set_banner。

setInterval(function() { // pass an anonymous function, this gets executed after 42 seconds...
    set_banner('banner1'); // ...and then calls set_banner from within itself
}, 42000);

Answer 2

需要考虑的其他事项：http://zetafleet.com/blog/why-i-consider-setinterval-harmful。（tl：dr而不是setInterval，使用setTimeout。）虽然我不确定他的论点是否适用于此，但养成避免习惯似乎是件好事。

function defer_banner(div, bannerArray, delay) {
  setTimeout(function() {
    setBanner(div, bannerArray);
    defer_banner(div, bannerArray, delay);
  }, delay); 
});

使用对象引用调用setinterval

2 个答案: