我正在尝试检测是否使用 JS chop 了文本。解决方案mentioned here除了下面的边缘情况外,效果很好。您会注意到,如果文本在视觉上被 chop ,则鼠标悬停的第一个 block 将返回 false。
function isEllipsisActive(e) {
return (e.offsetWidth < e.scrollWidth);
}
function onMouseHover(e) {
console.log(`is truncated: ${isEllipsisActive(e)}`);
}
div.red {
margin-bottom: 1em;
background: red;
color: #fff;
white-space: nowrap;
overflow: hidden;
text-overflow: ellipsis;
width: 300px;
cursor: pointer;
}
<h6>Hover mouse and watch for console messages.</h6>
<!-- should return true -->
<div class="red" onmouseover="onMouseHover(this)">
<a>Analytics reports comes through garbled. Plsss</a>
</div>
<!-- should return true -->
<div class="red" onmouseover="onMouseHover(this)">
<a>Analytics reports comes through garbled. Plsssssss</a>
</div>
<!-- should return false -->
<div class="red" onmouseover="onMouseHover(this)">
<a>Normal text</a>
</div>
我所追求的解决方案是让函数在文本被 css chop 时返回 true。
最佳答案
这里的问题是 HTMLElement.offsetWidth
和 Element.scrollWidth
是四舍五入的值。
您的元素的真正内部宽度实际上是 300.40625px
在我的电脑上,这会变成 300px
在我的 Chrome 中。
这里的解决方案是使用返回浮点值的 API,并且没有太多...
人们可能会想检查内部 <a>
的 getBoundingClientRect().width
,这实际上适用于所有 OP 的情况,但这仅适用于这些情况:向 div 添加填充,为这些 <a>
添加边距,或其他元素,它已损坏。
document.querySelectorAll( ".test" ).forEach( el => {
el.classList.toggle( "truncated", isEllipsisActive( el ) );
} );
function isEllipsisActive( el ) {
return el.firstElementChild.getBoundingClientRect().width > el.getBoundingClientRect().width;
}
div.test {
margin-bottom: 1em;
background: red;
color: #fff;
white-space: nowrap;
overflow: hidden;
text-overflow: ellipsis;
width: 300px;
}
div.truncated {
background: green;
}
.margin-left {
margin-left: 225px;
}
<!-- should be green -->
<div class="test">
<a>Analytics reports comes through garbled. Plsss</a>
</div>
<!-- should be green -->
<div class="test">
<a>Analytics reports comes through garbled. Plsssssss</a>
</div>
<!-- should be green -->
<div class="test">
<a>Analytics</a><a> reports comes through garbled. Plsssssss</a>
</div>
<!-- should be green -->
<div class="test">
<a class="margin-left">Shorter text</a>
</div>
<!-- should be red -->
<div class="test">
<a>Normal text</a>
</div>
所以有人可能会认为 Range及其
getBoundingClientRect()
然而,方法可以做到,虽然这能够告诉 的实际大小文字 元素中的内容,这仅检查 文字 内容。如果滚动是由边距引起的,它将不起作用。document.querySelectorAll(".test").forEach( el => {
el.classList.toggle( "truncated", isEllipsisActive( el ) );
} );
function isEllipsisActive( el ) {
return el.scrollWidth !== el.offsetWidth ?
el.scrollWidth > el.offsetWidth :
checkRanges( el ); // Blink and Webkit browsers do floor scrollWidth
}
function checkRanges( el ) {
const range = new Range();
range.selectNodeContents( el );
const range_rect = range.getBoundingClientRect();
const el_rect = el.getBoundingClientRect();
// assumes ltr direction
return range_rect.right > el_rect.right;
}
div.test {
margin-bottom: 1em;
background: red;
color: #fff;
white-space: nowrap;
overflow: hidden;
text-overflow: ellipsis;
width: 300px;
}
div.truncated {
background: green;
}
.margin-left {
margin-left: 225px;
}
.margin-right {
margin-right: 225px;
}
<!-- should be green -->
<div class="test">
<a>Analytics reports comes through garbled. Plsss</a>
</div>
<!-- should be green -->
<div class="test">
<a>Analytics reports comes through garbled. Plsssssss</a>
</div>
<!-- should be green -->
<div class="test">
<a>Analytics</a><a> reports comes through garbled. Plsssssss</a>
</div>
<!-- should be green -->
<div class="test">
<a class="margin-left">Shorter text</a>
</div>
<!-- should be green -->
<div class="test">
<a class="margin-right">Shorter text</a>
</div>
<!-- should be red -->
<div class="test">
<a>Normal text</a>
</div>
所以我能想到的唯一解决方案依赖于 Chrome 的特定行为:它们确实在
Range.getClientRects()
的结果中公开了渲染省略号的客户端矩形。 .所以肯定知道的方法,在 Chrome ,如果呈现省略号,则切换
text-overflow
属性并检查此 DOMRect 是否出现。但是,由于这是 Chrome 独有的行为,我们仍然需要检查 Safari 的 Range 边界框位置。
document.querySelectorAll(".test").forEach( el => {
el.classList.toggle( "truncated", isEllipsisActive( el ) );
} );
function isEllipsisActive( el ) {
return el.scrollWidth !== el.offsetWidth ?
el.scrollWidth > el.offsetWidth :
checkRanges( el ); // Blink and Webkit browsers do floor scrollWidth
}
function checkRanges( el ) {
const range = new Range();
range.selectNodeContents( el );
const range_rect = range.getBoundingClientRect();
const el_rect = el.getBoundingClientRect();
// assumes ltr direction
if( range_rect.right > el_rect.right ) {
return true;
}
// Following check would be enough for Blink browsers
// but they are the only ones exposing this behavior.
// first force ellipsis
el.classList.add( "text-overflow-ellipsis" );
// get all the client rects (there should be one for the ellipsis)
const rects_ellipsis = range.getClientRects();
// force no ellipsis
el.classList.add( "text-overflow-clip" );
const rects_clipped = range.getClientRects();
// clean
el.classList.remove( "text-overflow-ellipsis" );
el.classList.remove( "text-overflow-clip" );
// if the counts changed, the text is truncated
return rects_clipped.length !== rects_ellipsis.length;
}
/* 2 new clasess to force the rendering of ellipsis */
.text-overflow-ellipsis {
text-overflow: ellipsis !important;
}
.text-overflow-clip {
text-overflow: clip !important;
}
div.test {
margin-bottom: 1em;
background: red;
color: #fff;
white-space: nowrap;
overflow: hidden;
text-overflow: ellipsis;
width: 300px;
}
div.truncated {
background: green;
}
.margin-left {
margin-left: 225px;
}
.margin-right {
margin-right: 225px;
}
<!-- should be green -->
<div class="test">
<a>Analytics reports comes through garbled. Plsss</a>
</div>
<!-- should be green -->
<div class="test">
<a>Analytics reports comes through garbled. Plsssssss</a>
</div>
<!-- should be green -->
<div class="test">
<a>Analytics</a><a> reports comes through garbled. Plsssssss</a>
</div>
<!-- should be green -->
<div class="test">
<a class="margin-left">Shorter text</a>
</div>
<!-- should be green -->
<div class="test">
<a class="margin-right">Shorter text</a>
</div>
<!-- should be red -->
<div class="test">
<a>Normal text</a>
</div>
关于javascript - 如何使用Javascript检查文本是否被CSS chop ,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/64689074/