我想使用JavaScript来计算字符串的宽度。如果不使用单行字体,这可能吗?

如果它不是内置的,我唯一的想法是为每个字符创建一个宽度表,但这是非常不合理的,特别是支持Unicode和不同的类型大小(以及所有浏览器)。


当前回答

下面的代码片段,“计算”span标签的宽度,如果它太长,就添加“…”,并减少文本长度,直到它适合它的父标签(或者直到它尝试了超过1000次)

CSS

div.places {
  width : 100px;
}
div.places span {
  white-space:nowrap;
  overflow:hidden;
}

HTML

<div class="places">
  <span>This is my house</span>
</div>
<div class="places">
  <span>And my house are your house</span>
</div>
<div class="places">
  <span>This placename is most certainly too wide to fit</span>
</div>

JavaScript(使用jQuery)

// loops elements classed "places" and checks if their child "span" is too long to fit
$(".places").each(function (index, item) {
    var obj = $(item).find("span");
    if (obj.length) {
        var placename = $(obj).text();
        if ($(obj).width() > $(item).width() && placename.trim().length > 0) {
            var limit = 0;
            do {
                limit++;
                                    placename = placename.substring(0, placename.length - 1);
                                    $(obj).text(placename + "...");
            } while ($(obj).width() > $(item).width() && limit < 1000)
        }
    }
});

其他回答

嘿,大家,我知道我来晚了一点,但我们开始吧

window.addEventListener("error",function(e){ alert(e.message); });
var canvas = new OffscreenCanvas(400, 50);
var ctx = canvas.getContext("2d");
ctx.font = "16px Ariel"; //this can be dynamic using getComputedStyle
const chars = ["a","b","c","d","e","f"," ","    "];
const charWidths = new Map();
while(chars.length > 0){
  var char = chars.shift();
  var wide = ctx.measureText(char).width;
  charWidths.set(char,wide);
}

然后你可以用它来做如下的事情:

var pixelWidth = charWidths.get("0");
//fyi css properties like letter-spacing need to be accounted for

我使用文本度量包。工作真的很好,我尝试了这个解决方案,但在某些原因,它计算错误。

textMetrics.init(document.querySelector('h1'), { fontSize: '20px' });

textMetrics.init({
  fontSize: '14px',
  lineHeight: '20px',
  fontFamily: 'Helvetica, Arial, sans-serif',
  fontWeight: 400,
  width: 100,
});

这对我很有用……

// Handy JavaScript to measure the size taken to render the supplied text;
// you can supply additional style information too if you have it.

function measureText(pText, pFontSize, pStyle) {
    var lDiv = document.createElement('div');

    document.body.appendChild(lDiv);

    if (pStyle != null) {
        lDiv.style = pStyle;
    }
    lDiv.style.fontSize = "" + pFontSize + "px";
    lDiv.style.position = "absolute";
    lDiv.style.left = -1000;
    lDiv.style.top = -1000;

    lDiv.textContent = pText;

    var lResult = {
        width: lDiv.clientWidth,
        height: lDiv.clientHeight
    };

    document.body.removeChild(lDiv);
    lDiv = null;

    return lResult;
}

你可以使用画布,这样你就不必处理这么多css属性:

var canvas = document.createElement("canvas");
var ctx = canvas.getContext("2d");
ctx.font = "20pt Arial";  // This can be set programmaticly from the element's font-style if desired
var textWidth = ctx.measureText($("#myElement").text()).width;

下面的代码片段,“计算”span标签的宽度,如果它太长,就添加“…”,并减少文本长度,直到它适合它的父标签(或者直到它尝试了超过1000次)

CSS

div.places {
  width : 100px;
}
div.places span {
  white-space:nowrap;
  overflow:hidden;
}

HTML

<div class="places">
  <span>This is my house</span>
</div>
<div class="places">
  <span>And my house are your house</span>
</div>
<div class="places">
  <span>This placename is most certainly too wide to fit</span>
</div>

JavaScript(使用jQuery)

// loops elements classed "places" and checks if their child "span" is too long to fit
$(".places").each(function (index, item) {
    var obj = $(item).find("span");
    if (obj.length) {
        var placename = $(obj).text();
        if ($(obj).width() > $(item).width() && placename.trim().length > 0) {
            var limit = 0;
            do {
                limit++;
                                    placename = placename.substring(0, placename.length - 1);
                                    $(obj).text(placename + "...");
            } while ($(obj).width() > $(item).width() && limit < 1000)
        }
    }
});