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

根据Deepak Nadar的回答,我修改了函数参数,以接受文本和字体样式。您不需要引用元素。此外,fontOptions有默认值,所以您不需要提供所有的选项。

(function($) { $.format = function(format) { return (function(format, args) { return format.replace(/{(\d+)}/g, function(val, pos) { return typeof args[pos] !== 'undefined' ? args[pos] : val; }); }(format, [].slice.call(arguments, 1))); }; $.measureText = function(html, fontOptions) { fontOptions = $.extend({ fontSize: '1em', fontStyle: 'normal', fontWeight: 'normal', fontFamily: 'arial' }, fontOptions); var $el = $('<div>', { html: html, css: { position: 'absolute', left: -1000, top: -1000, display: 'none' } }).appendTo('body'); $(fontOptions).each(function(index, option) { $el.css(option, fontOptions[option]); }); var h = $el.outerHeight(), w = $el.outerWidth(); $el.remove(); return { height: h, width: w }; }; }(jQuery)); var dimensions = $.measureText("Hello World!", { fontWeight: 'bold', fontFamily: 'arial' }); // Font Dimensions: 94px x 18px $('body').append('<p>').text($.format('Font Dimensions: {0}px x {1}px', dimensions.width, dimensions.height)); <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

其他回答

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)
        }
    }
});

我为此写了一个小工具。也许对某些人有用。它不需要jQuery也能工作。

https://github.com/schickling/calculate-size

用法:

var size = calculateSize("Hello world!", {
   font: 'Arial',
   fontSize: '12px'
});

console.log(size.width); // 65
console.log(size.height); // 14

小提琴:http://jsfiddle.net/PEvL8/

更好的方法是在显示元素之前检测文本是否合适。你可以使用这个函数它不需要元素在屏幕上。

function textWidth(text, fontProp) {
    var tag = document.createElement("div");
    tag.style.position = "absolute";
    tag.style.left = "-999em";
    tag.style.whiteSpace = "nowrap";
    tag.style.font = fontProp;
    tag.innerHTML = text;

    document.body.appendChild(tag);

    var result = tag.clientWidth;

    document.body.removeChild(tag);

    return result;
}

用法:

if ( textWidth("Text", "bold 13px Verdana") > elementWidth) {
    ...
}

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;

如果有人在这里寻找一种测量字符串宽度的方法,以及一种知道适合特定宽度的最大字体大小的方法,这里有一个基于@Domi的解决方案的函数,使用二进制搜索:

/**
 * Find the largest font size (in pixels) that allows the string to fit in the given width.
 * 
 * @param {String} text - The text to be rendered.
 * @param {String} font - The css font descriptor that text is to be rendered with (e.g. "bold ?px verdana") -- note the use of ? in place of the font size.
 * @param {Number} width - The width in pixels the string must fit in
 * @param {Number} minFontPx - The smallest acceptable font size in pixels
 * @param {Number} maxFontPx - The largest acceptable font size in pixels
 **/
function GetTextSizeForWidth(text, font, width, minFontPx, maxFontPx) {
  for (;;) {
    var s = font.replace("?", maxFontPx);
    var w = GetTextWidth(text, s);
    if (w <= width) {
      return maxFontPx;
    }

    var g = (minFontPx + maxFontPx) / 2;

    if (Math.round(g) == Math.round(minFontPx) || Math.round(g) == Math.round(maxFontPx)) {
      return g;
    }

    s = font.replace("?", g);
    w = GetTextWidth(text, s);
    if (w >= width) {
      maxFontPx = g;
    } else {
      minFontPx = g;
    }
  }
}