您的代码有几个问题。
- 为什么
/ 5
?字符的宽度取决于font-family
和font-size
。
- 您必须在缩写标题中转义
str
(否则 " 将使代码无效)。
diff
未声明并在全局范围内结束
substring
不应该那样工作。你使用的是什么浏览器?
hidden
不是 的有效值style.display
。要隐藏它,您应该使用该值none
,但浏览器不计算offsetWidth
. 改为使用style.visibility="hidden"
。
- 寻找合适的长度是非常低效的。
- 必须逃走
</abbr>
”
我为您重写并添加了它,className
以便您可以使用样式来设置font-family
and font-size
。Fooz 先生建议您使用鼠标悬停来显示整个字符串。这不是必需的,因为现代浏览器会为您执行此操作(已使用 FF、IE、Opera 和 Chrome 进行测试)
function fitStringToSize(str,len,className) {
var result = str; // set the result to the whole string as default
var span = document.createElement("span");
span.className=className; //Allow a classname to be set to get the right font-size.
span.style.visibility = 'hidden';
span.style.padding = '0px';
document.body.appendChild(span);
// check if the string don't fit
span.innerHTML = result;
if (span.offsetWidth > len) {
var posStart = 0, posMid, posEnd = str.length;
while (true) {
// Calculate the middle position
posMid = posStart + Math.ceil((posEnd - posStart) / 2);
// Break the loop if this is the last round
if (posMid==posEnd || posMid==posStart) break;
span.innerHTML = str.substring(0,posMid) + '…';
// Test if the width at the middle position is
// too wide (set new end) or too narrow (set new start).
if ( span.offsetWidth > len ) posEnd = posMid; else posStart=posMid;
}
//Escape
var title = str.replace("\"",""");
//Escape < and >
var body = str.substring(0,posStart).replace("<","<").replace(">",">");
result = '<abbr title="' + title + '">' + body + '…<\/abbr>';
}
document.body.removeChild(span);
return result;
}
编辑:在进行更多测试时,我发现了一些错误。
改进:
- 转义复制到所有位置跨度的字符串。您仍然可以使用 html-entities,但不允许使用标签(
<
并将>
显示)
- 重写了
while
-statement(它有点快,但主要是为了摆脱导致额外回合的错误并摆脱break-statement)
- 将函数重命名为
fitStringToWidth
版本 2:
function fitStringToWidth(str,width,className) {
// str A string where html-entities are allowed but no tags.
// width The maximum allowed width in pixels
// className A CSS class name with the desired font-name and font-size. (optional)
// ----
// _escTag is a helper to escape 'less than' and 'greater than'
function _escTag(s){ return s.replace("<","<").replace(">",">");}
//Create a span element that will be used to get the width
var span = document.createElement("span");
//Allow a classname to be set to get the right font-size.
if (className) span.className=className;
span.style.display='inline';
span.style.visibility = 'hidden';
span.style.padding = '0px';
document.body.appendChild(span);
var result = _escTag(str); // default to the whole string
span.innerHTML = result;
// Check if the string will fit in the allowed width. NOTE: if the width
// can't be determined (offsetWidth==0) the whole string will be returned.
if (span.offsetWidth > width) {
var posStart = 0, posMid, posEnd = str.length, posLength;
// Calculate (posEnd - posStart) integer division by 2 and
// assign it to posLength. Repeat until posLength is zero.
while (posLength = (posEnd - posStart) >> 1) {
posMid = posStart + posLength;
//Get the string from the beginning up to posMid;
span.innerHTML = _escTag(str.substring(0,posMid)) + '…';
// Check if the current width is too wide (set new end)
// or too narrow (set new start)
if ( span.offsetWidth > width ) posEnd = posMid; else posStart=posMid;
}
result = '<abbr title="' +
str.replace("\"",""") + '">' +
_escTag(str.substring(0,posStart)) +
'…<\/abbr>';
}
document.body.removeChild(span);
return result;
}