javascript JS - 线夹紧

Posted 2021-05-03

/*!
* Clamp.js 0.5.1
*
* Copyright 2011-2013, Joseph Schmitt http://joe.sh
* Released under the WTFPL license
* http://sam.zoy.org/wtfpl/
*/
(function(){window.$clamp=function(c,d){function s(a,b){n.getComputedStyle||(n.getComputedStyle=function(a,b){this.el=a;this.getPropertyValue=function(b){var c=/(\-([a-z]){1})/g;"float"==b&&(b="styleFloat");c.test(b)&&(b=b.replace(c,function(a,b,c){return c.toUpperCase()}));return a.currentStyle&&a.currentStyle[b]?a.currentStyle[b]:null};return this});return n.getComputedStyle(a,null).getPropertyValue(b)}function t(a){a=a||c.clientHeight;var b=u(c);return Math.max(Math.floor(a/b),0)}function x(a){return u(c)*
a}function u(a){var b=s(a,"line-height");"normal"==b&&(b=1.2*parseInt(s(a,"font-size")));return parseInt(b)}function l(a){if(a.lastChild.children&&0<a.lastChild.children.length)return l(Array.prototype.slice.call(a.children).pop());if(a.lastChild&&a.lastChild.nodeValue&&""!=a.lastChild.nodeValue&&a.lastChild.nodeValue!=b.truncationChar)return a.lastChild;a.lastChild.parentNode.removeChild(a.lastChild);return l(c)}function p(a,d){if(d){var e=a.nodeValue.replace(b.truncationChar,"");f||(h=0<k.length?
k.shift():"",f=e.split(h));1<f.length?(q=f.pop(),r(a,f.join(h))):f=null;m&&(a.nodeValue=a.nodeValue.replace(b.truncationChar,""),c.innerHTML=a.nodeValue+" "+m.innerHTML+b.truncationChar);if(f){if(c.clientHeight<=d)if(0<=k.length&&""!=h)r(a,f.join(h)+h+q),f=null;else return c.innerHTML}else""==h&&(r(a,""),a=l(c),k=b.splitOnChars.slice(0),h=k[0],q=f=null);if(b.animate)setTimeout(function(){p(a,d)},!0===b.animate?10:b.animate);else return p(a,d)}}function r(a,c){a.nodeValue=c+b.truncationChar}d=d||{};
var n=window,b={clamp:d.clamp||2,useNativeClamp:"undefined"!=typeof d.useNativeClamp?d.useNativeClamp:!0,splitOnChars:d.splitOnChars||[".","-","\u2013","\u2014"," "],animate:d.animate||!1,truncationChar:d.truncationChar||"\u2026",truncationHTML:d.truncationHTML},e=c.style,y=c.innerHTML,z="undefined"!=typeof c.style.webkitLineClamp,g=b.clamp,v=g.indexOf&&(-1<g.indexOf("px")||-1<g.indexOf("em")),m;b.truncationHTML&&(m=document.createElement("span"),m.innerHTML=b.truncationHTML);var k=b.splitOnChars.slice(0),
h=k[0],f,q;"auto"==g?g=t():v&&(g=t(parseInt(g)));var w;z&&b.useNativeClamp?(e.overflow="hidden",e.textOverflow="ellipsis",e.webkitBoxOrient="vertical",e.display="-webkit-box",e.webkitLineClamp=g,v&&(e.height=b.clamp+"px")):(e=x(g),e<=c.clientHeight&&(w=p(l(c),e)));return{original:y,clamped:w}}})();

Clamps (ie. cuts off) an HTML element's content by adding ellipsis to it if the 
content inside is too long.


# Sample Usage

<pre>
//Single line
$clamp(myHeader, {clamp: 1});

//Multi-line
$clamp(myHeader, {clamp: 3});

//Auto-clamp based on available height
$clamp(myParagraph, {clamp: 'auto'});

//Auto-clamp based on a fixed element height
$clamp(myParagraph, {clamp: '35px'});
</pre>

The $clamp method is the primary way of interacting with Clamp.js, and it takes two
arguments. The first is the element which should be clamped, and the second is an
Object with options in JSON notation.


# Options

**clamp** _(Number | String | 'auto')_. This controls where and when to clamp the 
text of an element. Submitting a number controls the number of lines that should
be displayed. Second, you can submit a CSS value (in px or em) that controls the
height of the element as a String. Finally, you can submit the word 'auto' as a string.
Auto will try to fill up the available space with the content and then automatically
clamp once content no longer fits. This last option should only be set if a static 
height is being set on the element elsewhere (such as through CSS) otherwise no 
clamping will be done.

**useNativeClamp** _(Boolean)_. Enables or disables using the native -webkit-line-clamp
in a supported browser (ie. Webkit). It defaults to true if you're using Webkit,
but it can behave wonky sometimes so you can set it to false to use the JavaScript-
based solution.

**truncationChar** _(String)_. The character to insert at the end of the HTML element
after truncation is performed. This defaults to an ellipsis (…).

**truncationHTML** _(String)_. A string of HTML to insert before the truncation character.
This is useful if you'd like to add a "Read more" link or some such thing at the end of
your clamped node.

**splitOnChars** _(Array)_. Determines what characters to use to chunk an element into
smaller pieces. Version 0.1 of Clamp.js would always remove each individual character
to check for fit. With v0.2, you now have an option to pass a list of characters it
can use. For example, it you pass an array of ['.', ',', ' '] then it will first remove
sentences, then remove comma-phrases, and remove words, and finally remove individual
characters to try and find the correct height. This will lead to increased performance
and less looping when removing larger pieces of text (such as in paragraphs). The default
is set to remove sentences (periods), hypens, en-dashes, em-dashes, and finally words 
(spaces). Removing by character is always enabled as the last attempt no matter what
is submitted in the array.

**animate** _(Boolean)_. Silly little easter-egg that, when set to true, will animate
removing individual characters from the end of the element until the content fits.
Defaults to false.

/*!
* Clamp.js 0.5.1
*
* Copyright 2011-2013, Joseph Schmitt http://joe.sh
* Released under the WTFPL license
* http://sam.zoy.org/wtfpl/
*/

(function(){
    /**
     * Clamps a text node.
     * @param {HTMLElement} element. Element containing the text node to clamp.
     * @param {Object} options. Options to pass to the clamper.
     */
    function clamp(element, options) {
        options = options || {};

        var self = this,
            win = window,
            opt = {
                clamp:              options.clamp || 2,
                useNativeClamp:     typeof(options.useNativeClamp) != 'undefined' ? options.useNativeClamp : true,
                splitOnChars:       options.splitOnChars || ['.', '-', '–', '—', ' '], //Split on sentences (periods), hypens, en-dashes, em-dashes, and words (spaces).
                animate:            options.animate || false,
                truncationChar:     options.truncationChar || '…',
                truncationHTML:     options.truncationHTML
            },

            sty = element.style,
            originalText = element.innerHTML,

            supportsNativeClamp = typeof(element.style.webkitLineClamp) != 'undefined',
            clampValue = opt.clamp,
            isCSSValue = clampValue.indexOf && (clampValue.indexOf('px') > -1 || clampValue.indexOf('em') > -1),
            truncationHTMLContainer;
            
        if (opt.truncationHTML) {
            truncationHTMLContainer = document.createElement('span');
            truncationHTMLContainer.innerHTML = opt.truncationHTML;
        }


// UTILITY FUNCTIONS __________________________________________________________

        /**
         * Return the current style for an element.
         * @param {HTMLElement} elem The element to compute.
         * @param {string} prop The style property.
         * @returns {number}
         */
        function computeStyle(elem, prop) {
            if (!win.getComputedStyle) {
                win.getComputedStyle = function(el, pseudo) {
                    this.el = el;
                    this.getPropertyValue = function(prop) {
                        var re = /(\-([a-z]){1})/g;
                        if (prop == 'float') prop = 'styleFloat';
                        if (re.test(prop)) {
                            prop = prop.replace(re, function () {
                                return arguments[2].toUpperCase();
                            });
                        }
                        return el.currentStyle && el.currentStyle[prop] ? el.currentStyle[prop] : null;
                    }
                    return this;
                }
            }

            return win.getComputedStyle(elem, null).getPropertyValue(prop);
        }

        /**
         * Returns the maximum number of lines of text that should be rendered based
         * on the current height of the element and the line-height of the text.
         */
        function getMaxLines(height) {
            var availHeight = height || element.clientHeight,
                lineHeight = getLineHeight(element);

            return Math.max(Math.floor(availHeight/lineHeight), 0);
        }

        /**
         * Returns the maximum height a given element should have based on the line-
         * height of the text and the given clamp value.
         */
        function getMaxHeight(clmp) {
            var lineHeight = getLineHeight(element);
            return lineHeight * clmp;
        }

        /**
         * Returns the line-height of an element as an integer.
         */
        function getLineHeight(elem) {
            var lh = computeStyle(elem, 'line-height');
            if (lh == 'normal') {
                // Normal line heights vary from browser to browser. The spec recommends
                // a value between 1.0 and 1.2 of the font size. Using 1.1 to split the diff.
                lh = parseInt(computeStyle(elem, 'font-size')) * 1.2;
            }
            return parseInt(lh);
        }


// MEAT AND POTATOES (MMMM, POTATOES...) ______________________________________
        var splitOnChars = opt.splitOnChars.slice(0),
            splitChar = splitOnChars[0],
            chunks,
            lastChunk;
        
        /**
         * Gets an element's last child. That may be another node or a node's contents.
         */
        function getLastChild(elem) {
            //Current element has children, need to go deeper and get last child as a text node
            if (elem.lastChild.children && elem.lastChild.children.length > 0) {
                return getLastChild(Array.prototype.slice.call(elem.children).pop());
            }
            //This is the absolute last child, a text node, but something's wrong with it. Remove it and keep trying
            else if (!elem.lastChild || !elem.lastChild.nodeValue || elem.lastChild.nodeValue == '' || elem.lastChild.nodeValue == opt.truncationChar) {
                elem.lastChild.parentNode.removeChild(elem.lastChild);
                return getLastChild(element);
            }
            //This is the last child we want, return it
            else {
                return elem.lastChild;
            }
        }
        
        /**
         * Removes one character at a time from the text until its width or
         * height is beneath the passed-in max param.
         */
        function truncate(target, maxHeight) {
            if (!maxHeight) {return;}
            
            /**
             * Resets global variables.
             */
            function reset() {
                splitOnChars = opt.splitOnChars.slice(0);
                splitChar = splitOnChars[0];
                chunks = null;
                lastChunk = null;
            }
            
            var nodeValue = target.nodeValue.replace(opt.truncationChar, '');
            
            //Grab the next chunks
            if (!chunks) {
                //If there are more characters to try, grab the next one
                if (splitOnChars.length > 0) {
                    splitChar = splitOnChars.shift();
                }
                //No characters to chunk by. Go character-by-character
                else {
                    splitChar = '';
                }
                
                chunks = nodeValue.split(splitChar);
            }
            
            //If there are chunks left to remove, remove the last one and see if
            // the nodeValue fits.
            if (chunks.length > 1) {
                // console.log('chunks', chunks);
                lastChunk = chunks.pop();
                // console.log('lastChunk', lastChunk);
                applyEllipsis(target, chunks.join(splitChar));
            }
            //No more chunks can be removed using this character
            else {
                chunks = null;
            }
            
            //Insert the custom HTML before the truncation character
            if (truncationHTMLContainer) {
                target.nodeValue = target.nodeValue.replace(opt.truncationChar, '');
                element.innerHTML = target.nodeValue + ' ' + truncationHTMLContainer.innerHTML + opt.truncationChar;
            }

            //Search produced valid chunks
            if (chunks) {
                //It fits
                if (element.clientHeight <= maxHeight) {
                    //There's still more characters to try splitting on, not quite done yet
                    if (splitOnChars.length >= 0 && splitChar != '') {
                        applyEllipsis(target, chunks.join(splitChar) + splitChar + lastChunk);
                        chunks = null;
                    }
                    //Finished!
                    else {
                        return element.innerHTML;
                    }
                }
            }
            //No valid chunks produced
            else {
                //No valid chunks even when splitting by letter, time to move
                //on to the next node
                if (splitChar == '') {
                    applyEllipsis(target, '');
                    target = getLastChild(element);
                    
                    reset();
                }
            }
            
            //If you get here it means still too big, let's keep truncating
            if (opt.animate) {
                setTimeout(function() {
                    truncate(target, maxHeight);
                }, opt.animate === true ? 10 : opt.animate);
            }
            else {
                return truncate(target, maxHeight);
            }
        }
        
        function applyEllipsis(elem, str) {
            elem.nodeValue = str + opt.truncationChar;
        }


// CONSTRUCTOR ________________________________________________________________

        if (clampValue == 'auto') {
            clampValue = getMaxLines();
        }
        else if (isCSSValue) {
            clampValue = getMaxLines(parseInt(clampValue));
        }

        var clampedText;
        if (supportsNativeClamp && opt.useNativeClamp) {
            sty.overflow = 'hidden';
            sty.textOverflow = 'ellipsis';
            sty.webkitBoxOrient = 'vertical';
            sty.display = '-webkit-box';
            sty.webkitLineClamp = clampValue;

            if (isCSSValue) {
                sty.height = opt.clamp + 'px';
            }
        }
        else {
            var height = getMaxHeight(clampValue);
            if (height <= element.clientHeight) {
                clampedText = truncate(getLastChild(element), height);
            }
        }
        
        return {
            'original': originalText,
            'clamped': clampedText
        }
    }

    window.$clamp = clamp;
})();