jquery - 基本 var 语法 : Variable already defined?

Question

我有以下代码，用于测试浏览器视口(viewport)中是否存在元素:

(function ($) {
$.fn.visible = function (partial, hidden, direction) {

    var $t = $(this).eq(0),
        t = $t.get(0),
        $w = $(window),
        viewTop = $w.scrollTop(),
        viewBottom = viewTop + $w.height(),
        viewLeft = $w.scrollLeft(),
        viewRight = viewLeft + $w.width(),
        _top = $t.offset().top,
        _bottom = _top + $t.height(),
        _left = $t.offset().left,
        _right = _left + $t.width(),
        compareTop = partial === true ? _bottom : _top,
        compareBottom = partial === true ? _top : _bottom,
        compareLeft = partial === true ? _right : _left,
        compareRight = partial === true ? _left : _right,
        clientSize = hidden === true ? t.offsetWidth * t.offsetHeight : true,
        direction = (direction) ? direction : 'both';

    if (direction === 'both') return !!clientSize && ((compareBottom <= viewBottom) && (compareTop >= viewTop)) && ((compareRight <= viewRight) && (compareLeft >= viewLeft));
    else if (direction === 'vertical') return !!clientSize && ((compareBottom <= viewBottom) && (compareTop >= viewTop));
    else if (direction === 'horizontal') return !!clientSize && ((compareRight <= viewRight) && (compareLeft >= viewLeft));
};

})(jQuery);

但是，当我通过 JS lint 运行此命令时，我收到一条错误，指出 direction 已定义。我的语法哪里错了？

(脚本仍然有效)

Answer 1

direction 是参数名称​​并且您在函数内使用 var Direction 定义它。

如果将上一行的逗号更改为分号，即使 direction = ... 不是 var 语句的一部分，那就没问题了。