问题是控制台中显示包含的错误。有人能帮我理解为什么会这样吗？我不久前开始学习jQuery，但我还是很新。请帮助我指出正确的方向。
“维度：jQuery集合为空”
(function($) {
var height = $.fn.height,
width = $.fn.width;
$.fn.extend({
height: function() {
if (!this[0]) error();
if (this[0] == window)
if (($.browser.mozilla || $.browser.opera) && $(document).width() > self.innerWidth) return self.innerHeight - getScrollbarWidth();
else
return self.innerHeight || $.boxModel && document.documentElement.clientHeight || document.body.clientHeight;
if (this[0] == document) return Math.max(document.body.scrollHeight, document.body.offsetHeight);
return height.apply(this, arguments);
},
width: function() {
if (!this[0]) error();
if (this[0] == window)
if (($.browser.mozilla || $.browser.opera) && $(document).height() > self.innerHeight) return self.innerWidth - getScrollbarWidth();
else
return self.innerWidth || $.boxModel && document.documentElement.clientWidth || document.body.clientWidth;
if (this[0] == document)
if ($.browser.mozilla) {
var scrollLeft = self.pageXOffset;
self.scrollTo(99999999, self.pageYOffset);
var scrollWidth = self.pageXOffset;
self.scrollTo(scrollLeft, self.pageYOffset);
return document.body.offsetWidth + scrollWidth;
} else
return Math.max(document.body.scrollWidth, document.body.offsetWidth);
return width.apply(this, arguments);
},
innerHeight: function() {
if (!this[0]) error();
return this[0] == window || this[0] == document ? this.height() : this.is(':visible') ? this[0].offsetHeight - num(this, 'borderTopWidth') - num(this, 'borderBottomWidth') : this.height() + num(this, 'paddingTop') + num(this, 'paddingBottom');
},
innerWidth: function() {
if (!this[0]) error();
return this[0] == window || this[0] == document ? this.width() : this.is(':visible') ? this[0].offsetWidth - num(this, 'borderLeftWidth') - num(this, 'borderRightWidth') : this.width() + num(this, 'paddingLeft') + num(this, 'paddingRight');
},
outerHeight: function(options) {
if (!this[0]) error();
options = $.extend({
margin: false
}, options || {});
return this[0] == window || this[0] == document ? this.height() : this.is(':visible') ? this[0].offsetHeight + (options.margin ? (num(this, 'marginTop') + num(this, 'marginBottom')) : 0) : this.height() + num(this, 'borderTopWidth') + num(this, 'borderBottomWidth') + num(this, 'paddingTop') + num(this, 'paddingBottom') + (options.margin ? (num(this, 'marginTop') + num(this, 'marginBottom')) : 0);
},
outerWidth: function(options) {
if (!this[0]) error();
options = $.extend({
margin: false
}, options || {});
return this[0] == window || this[0] == document ? this.width() : this.is(':visible') ? this[0].offsetWidth + (options.margin ? (num(this, 'marginLeft') + num(this, 'marginRight')) : 0) : this.width() + num(this, 'borderLeftWidth') + num(this, 'borderRightWidth') + num(this, 'paddingLeft') + num(this, 'paddingRight') + (options.margin ? (num(this, 'marginLeft') + num(this, 'marginRight')) : 0);
},
scrollLeft: function(val) {
if (!this[0]) error();
if (val != undefined) return this.each(function() {
if (this == window || this == document) window.scrollTo(val, $(window).scrollTop());
else
this.scrollLeft = val;
});
if (this[0] == window || this[0] == document) return self.pageXOffset || $.boxModel && document.documentElement.scrollLeft || document.body.scrollLeft;
return this[0].scrollLeft;
},
scrollTop: function(val) {
if (!this[0]) error();
if (val != undefined) return this.each(function() {
if (this == window || this == document) window.scrollTo($(window).scrollLeft(), val);
else
this.scrollTop = val;
});
if (this[0] == window || this[0] == document) return self.pageYOffset || $.boxModel && document.documentElement.scrollTop || document.body.scrollTop;
return this[0].scrollTop;
},
position: function(returnObject) {
return this.offset({
margin: false,
scroll: false,
relativeTo: this.offsetParent()
}, returnObject);
},
offset: function(options, returnObject) {
if (!this[0]) error();
var x = 0,
y = 0,
sl = 0,
st = 0,
elem = this[0],
parent = this[0],
op, parPos, elemPos = $.css(elem, 'position'),
mo = $.browser.mozilla,
ie = $.browser.msie,
oa = $.browser.opera,
sf = $.browser.safari,
sf3 = $.browser.safari && parseInt($.browser.version) > 520,
absparent = false,
relparent = false,
options = $.extend({
margin: true,
border: false,
padding: false,
scroll: true,
lite: false,
relativeTo: document.body
}, options || {});
if (options.lite) return this.offsetLite(options, returnObject);
if (options.relativeTo.jquery) options.relativeTo = options.relativeTo[0];
if (elem.tagName == 'BODY') {
x = elem.offsetLeft;
y = elem.offsetTop;
if (mo) {
x += num(elem, 'marginLeft') + (num(elem, 'borderLeftWidth') * 2);
y += num(elem, 'marginTop') + (num(elem, 'borderTopWidth') * 2);
} else
if (oa) {
x += num(elem, 'marginLeft');
y += num(elem, 'marginTop');
} else
if ((ie && jQuery.boxModel)) {
x += num(elem, 'borderLeftWidth');
y += num(elem, 'borderTopWidth');
} else
if (sf3) {
x += num(elem, 'marginLeft') + num(elem, 'borderLeftWidth');
y += num(elem, 'marginTop') + num(elem, 'borderTopWidth');
}
} else {
do {
parPos = $.css(parent, 'position');
x += parent.offsetLeft;
y += parent.offsetTop;
if (mo || ie || sf3) {
x += num(parent, 'borderLeftWidth');
y += num(parent, 'borderTopWidth');
if (mo && parPos == 'absolute') absparent = true;
if (ie && parPos == 'relative') relparent = true;
}
op = parent.offsetParent || document.body;
if (options.scroll || mo) {
do {
if (options.scroll) {
sl += parent.scrollLeft;
st += parent.scrollTop;
}
if (oa && ($.css(parent, 'display') || '').match(/table-row|inline/)) {
sl = sl - ((parent.scrollLeft == parent.offsetLeft) ? parent.scrollLeft : 0);
st = st - ((parent.scrollTop == parent.offsetTop) ? parent.scrollTop : 0);
}
if (mo && parent != elem && $.css(parent, 'overflow') != 'visible') {
x += num(parent, 'borderLeftWidth');
y += num(parent, 'borderTopWidth');
}
parent = parent.parentNode;
} while (parent != op);
}
parent = op;
if (parent == options.relativeTo && !(parent.tagName == 'BODY' || parent.tagName == 'HTML')) {
if (mo && parent != elem && $.css(parent, 'overflow') != 'visible') {
x += num(parent, 'borderLeftWidth');
y += num(parent, 'borderTopWidth');
}
if (((sf && !sf3) || oa) && parPos != 'static') {
x -= num(op, 'borderLeftWidth');
y -= num(op, 'borderTopWidth');
}
break;
}
if (parent.tagName == 'BODY' || parent.tagName == 'HTML') {
if (((sf && !sf3) || (ie && $.boxModel)) && elemPos != 'absolute' && elemPos != 'fixed') {
x += num(parent, 'marginLeft');
y += num(parent, 'marginTop');
}
if (sf3 || (mo && !absparent && elemPos != 'fixed') || (ie && elemPos == 'static' && !relparent)) {
x += num(parent, 'borderLeftWidth');
y += num(parent, 'borderTopWidth');
}
break;
}
} while (parent);
}
var returnValue = handleOffsetReturn(elem, options, x, y, sl, st);
if (returnObject) {
$.extend(returnObject, returnValue);
return this;
} else {
return returnValue;
}
},
offsetLite: function(options, returnObject) {
if (!this[0]) error();
var x = 0,
y = 0,
sl = 0,
st = 0,
parent = this[0],
offsetParent, options = $.extend({
margin: true,
border: false,
padding: false,
scroll: true,
relativeTo: document.body
}, options || {});
if (options.relativeTo.jquery) options.relativeTo = options.relativeTo[0];
do {
x += parent.offsetLeft;
y += parent.offsetTop;
offsetParent = parent.offsetParent || document.body;
if (options.scroll) {
do {
sl += parent.scrollLeft;
st += parent.scrollTop;
parent = parent.parentNode;
} while (parent != offsetParent);
}
parent = offsetParent;
} while (parent && parent.tagName != 'BODY' && parent.tagName != 'HTML' && parent != options.relativeTo);
var returnValue = handleOffsetReturn(this[0], options, x, y, sl, st);
if (returnObject) {
$.extend(returnObject, returnValue);
return this;
} else {
return returnValue;
}
},
offsetParent: function() {
if (!this[0]) error();
var offsetParent = this[0].offsetParent;
while (offsetParent && (offsetParent.tagName != 'BODY' && $.css(offsetParent, 'position') == 'static')) offsetParent = offsetParent.offsetParent;
return $(offsetParent);
}
});
var error = function() {
throw "Dimensions: jQuery collection is empty";
};
var num = function(el, prop) {
return parseInt($.css(el.jquery ? el[0] : el, prop)) || 0;
};
var handleOffsetReturn = function(elem, options, x, y, sl, st) {
if (!options.margin) {
x -= num(elem, 'marginLeft');
y -= num(elem, 'marginTop');
}
if (options.border && (($.browser.safari && parseInt($.browser.version) < 520) || $.browser.opera)) {
x += num(elem, 'borderLeftWidth');
y += num(elem, 'borderTopWidth');
} else if (!options.border && !(($.browser.safari && parseInt($.browser.version) < 520) || $.browser.opera)) {
x -= num(elem, 'borderLeftWidth');
y -= num(elem, 'borderTopWidth');
}
if (options.padding) {
x += num(elem, 'paddingLeft');
y += num(elem, 'paddingTop');
}
if (options.scroll && (!$.browser.opera || elem.offsetLeft != elem.scrollLeft && elem.offsetTop != elem.scrollLeft)) {
sl -= elem.scrollLeft;
st -= elem.scrollTop;
}
return options.scroll ? {
top: y - st,
left: x - sl,
scrollTop: st,
scrollLeft: sl
} : {
top: y,
left: x
};
};
var scrollbarWidth = 0;
var getScrollbarWidth = function() {
if (!scrollbarWidth) {
var testEl = $('<div>').css({
width: 100,
height: 100,
overflow: 'auto',
position: 'absolute',
top: -1000,
left: -1000
}).appendTo('body');
scrollbarWidth = 100 - testEl.append('<div>').find('div').css({
width: '100%',
height: 200
}).width();
testEl.remove();
}
return scrollbarWidth;
};
})(jQuery);
答案 0 :(得分：0)
(!this[0])为true时会调用错误函数。
这意味着您正在使用的对象应该是一个数组，并且第一个元素应该存在。
this[0]是数组的第一个元素。
this[0]将评估为true。
!(this[0])将评估为true。
答案 1 :(得分：0)
我认为你想验证this[0]是否有价值，或者它可能是空的。
尝试使用jquery提供的$ .isEmptyObject
例如：
if($.isEmptyObject(this[0])){
error();
}