Question

我正在尝试使用JQuery Waypoints来做换色标题。我有一个对象数组，显示单页网站的相关颜色部分（见下文）：

var colours = new Array(
    {section: 'home', colour: '#000'},
    {section: 'video-audio', colour: '#EF6E7C'},
    {section: 'motion-graphics', colour: '#FBC57A'},
    {section: 'graphic-design', colour: '#FFF9A9'},
    {section: 'web-development', colour: '#AAD693'},
    {section: 'social-media', colour: '#6D8DC9'},   
    {section: 'photography', colour: '#8A6FB0'},    
    {section: 'talent', colour: '#C57AB3'},     
    {section: 'contact', colour: '#000'}
);

然后我使用下面的脚本为每个部分创建JQuery Waypoint（在HTML中标记为<section id="...">）：

// top bar whose background-colour is being changed
var $topBar = $('.top-bar');

var offsetNum = 0, // pixels to offset waypoints
    animateTime = 300, // milliseconds to animate
    fallbackColour = '#333';

// len is number of sections (length of colours array)
var len = (typeof colours == 'undefined') ? 0 : colours.length;

if (len > 1) {
    for (var i = 0; i < len; i++) {
        var curColour = ('colour' in colours[i]) ? colours[i].colour : fallbackColour,
            curSection = ('section' in colours[i]) ? colours[i].section : 'unknown';

        $('#' + curSection).waypoint(function(direction) {
            if (i > 0 && i < len) {
                curColour = (direction === 'down') ?
                    (colours[i+1].hasOwnProperty('colour') ? colours[i+1].colour : fallbackColour) :
                    (curColour = colours[i-1].hasOwnProperty('colour') ? colours[i-1].colour : fallbackColour);
            }

            // first or last waypoint
            $topBar.stop().animate({backgroundColor: curColour}, animateTime);
        }, { offset: offsetNum });
    }
}

当我只为每个部分手动创建航点而不是使用对象数组和for循环时，它可以工作，但这是很多代码重复。如果稍后添加更多部分，我希望尽可能少地进行修改。

我在使用警报进行调试时发现，所有Waypoint都将i视为9（最大值） - 有没有办法将正确的i值传递给每个Waypoint直接，还是有更好的解决方法？

Answer 1

在调用回调时，var i的值为9（所有回调仍具有与i相同的引用）。所以你应该传递实际值。例如：

for (var i = 0; i < len; i++) {

    var curSection = ('section' in colours[i]) ? colours[i].section : 'unknown'; 

    addWaypoint(i, curSection);
}

function addWaypoint( n, curSection ){

    // n now has the value 0, 1, 2, etc. instead of referencing i

    $('#' + curSection).waypoint(function(direction) {
        console.log(i, direction); // 0, "down"
    });    
}

将变量传递给JQuery Waypoints

1 个答案: