JavaScript未捕获的SyntaxError:意外的令牌非法 [英] JavaScript Uncaught SyntaxError: Unexpected token ILLEGAL
问题描述
我试着在代码下运行,但chrome显示为意外的标记ILLEGAL 。
任何人都可以帮忙吗?
当我点击按钮时,它应该添加标签,当它找到 images / 1h.jpg 它不存在,它应该触发 onerror 事件并运行函数onc()添加一些CSS并加载另一张图片,但它没有运行函数onc( ),当我访问控制台时,它显示未捕获的SyntaxError:意外的标记ILLEGAL 。
$ b
< button id ='a'onclick =onc();> aaa< / button>< div>< / div>
function onc(){var path1 ='images / 1h.jpg'; //不存在var path2 ='images / 1s.jpg'; //存在var tmp =< img sr c ='+ path1 +'onerror ='nofind(this,+ path2 +);'/> ; $('div')。html(tmp);}
我搜索了一些答案, 或',但我真的不知道如何解决我的代码。谢谢。
在HTML属性文本中, path2
中的字符串不会被引用,它将如下所示:
onerror ='nofind(this,images / 1s.jpg);'
一个解决方案是将它放在引号中:
var tmp =< img src =' + path1 +'onerror ='nofind(this,\+ path2 +\);'/> ;
//变化在这里----------------------------------- ^^ - ------- ^^
...呈现如下:
onerror ='nofind(this,images / 1s.jpg);'
然而,更好的解决方案不是使用 onXyz
属性,没有理由而是使用现代事件处理:
function onc(){
var path1 ='images / 1h.jpg '; //不存在
var path2 ='images / 1s.jpg'; //存在
var img = $(img)on(error,function(){
nofind(this,path2);
})。attr(src,path1);
$('div')。html(img);
}
请注意,我们在错误
事件之前设置 src
属性。根据错误原因, load
事件,t可能会有相当大的影响。 (在设置 src
之后,您可以挂钩 load
事件是一个常见的误解;它最适用于但如果浏览器具有缓存的图像并且缓存设置允许浏览器在不重新验证它的情况下重用它,在这种情况下,浏览器可能会触发 load $>只要设置了
src
,并且没有看到任何JavaScript处理程序,就不会让它们排队,以便在JavaScript线程下次可以运行处理程序时运行。 [只有一个主要的JavaScript UI线程,但浏览器是多线程的。])
I tried to run below code but chrome showed Unexpected token ILLEGAL . Can anyone help ?
When I click the button, it should add the tag, and when it find images/1h.jpg it does not exist ,it should trigger onerrorevent and run function onc() to add some CSS and load another picture, but it didnt run function onc() and when I access console ,it shows Uncaught SyntaxError: Unexpected token ILLEGAL .
<button id='a' onclick="onc();">aaa</button>
<div></div>
function onc(){
var path1= 'images/1h.jpg';//Does not exist
var path2= 'images/1s.jpg';//exist
var tmp = "<img src='"+path1+"' onerror='nofind(this,"+path2+");' /> ";
$('div').html(tmp);
}
I searched some answers, it seems caused by "" or '', but I really don't know how to fix my code. Thanks.
In the rendered JavaScript in the HTML attribute text, the string you have in path2
won't be in quotes, it'll look like this:
onerror='nofind(this,images/1s.jpg);'
One solution is to put it in quotes:
var tmp = "<img src='"+path1+"' onerror='nofind(this,\""+path2+"\");' /> ";
// Change is here -----------------------------------^^---------^^
...which renders like this:
onerror='nofind(this,"images/1s.jpg");'
A better solution, though, would be not to use an onXyz
attribute at all. There's no reason to. Instead, use modern event handling:
function onc(){
var path1= 'images/1h.jpg';//Does not exist
var path2= 'images/1s.jpg';//exist
var img = $("img").on("error", function() {
nofind(this, path2);
}).attr("src", path1);
$('div').html(img);
}
Note that we hook the error
event before setting the src
attribute. This may not be strictly necessary with error
depending on the reason for the error, but it's a good habit to get into and it can matter quite a lot for the related load
event. (It's a common misconception that you can hook the load
event after setting src
; it works most of the time, but may not if the browser has the image cached and the cache settings for it allow the browser to reuse it without revalidating it, in which case the browser may fire the load
event as soon as src
is set and, not seeing any JavaScript handlers, doesn't queue them to run when the JavaScript thread is next free to run handlers. [There is only one main JavaScript UI thread, but browsers are multi-threaded.])
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