The DomHelper class provides a layer of abstraction from DOM and transparently supports creating * elements via DOM or using HTML fragments. It also has the ability to create HTML fragment templates * from your DOM building code.

* *

DomHelper element specification object

A specification object is used when creating elements. Attributes of this object * are assumed to be element attributes, except for 4 special attributes: *

tag :
The tag name of the element
children : or cn
An array of the * same kind of element definition objects to be created and appended. These can be nested * as deep as you want.
cls :
The class attribute of the element. * This will end up being either the "class" attribute on a HTML fragment or className * for a DOM node, depending on whether DomHelper is using fragments or DOM.
html :
The innerHTML for the element

* *

Insertion methods

Commonly used insertion methods: *

{@link #append} :
{@link #insertBefore} :
{@link #insertAfter} :
{@link #overwrite} :
{@link #createTemplate} :
{@link #insertHtml} :

* *

Example

This is an example, where an unordered list with 3 children items is appended to an existing * element with id 'my-div':


var dh = Ext.DomHelper; // create shorthand alias
// specification object
var spec = {
    id: 'my-ul',
    tag: 'ul',
    cls: 'my-list',
    // append children after creating
    children: [     // may also specify 'cn' instead of 'children'
        {tag: 'li', id: 'item0', html: 'List Item 0'},
        {tag: 'li', id: 'item1', html: 'List Item 1'},
        {tag: 'li', id: 'item2', html: 'List Item 2'}
    ]
};
var list = dh.append(
    'my-div', // the context element 'my-div' can either be the id or the actual node
    spec      // the specification object
);

Element creation specification parameters in this class may also be passed as an Array of * specification objects. This can be used to insert multiple sibling nodes into an existing * container very efficiently. For example, to add more list items to the example above:


dh.append('my-ul', [
    {tag: 'li', id: 'item3', html: 'List Item 3'},
    {tag: 'li', id: 'item4', html: 'List Item 4'}
]);
 *

* *

Templating

The real power is in the built-in templating. Instead of creating or appending any elements, * {@link #createTemplate} returns a Template object which can be used over and over to * insert new elements. Revisiting the example above, we could utilize templating this time: *


// create the node
var list = dh.append('my-div', {tag: 'ul', cls: 'my-list'});
// get template
var tpl = dh.createTemplate({tag: 'li', id: 'item{0}', html: 'List Item {0}'});

for(var i = 0; i < 5, i++){
    tpl.append(list, [i]); // use template to append to the actual node
}
 *

An example using a template:


var html = '{2}';

var tpl = new Ext.DomHelper.createTemplate(html);
tpl.append('blog-roll', ['link1', 'http://www.jackslocum.com/', "Jack's Site"]);
tpl.append('blog-roll', ['link2', 'http://www.dustindiaz.com/', "Dustin's Site"]);
 *

* *

The same example using named parameters:


var html = '{text}';

var tpl = new Ext.DomHelper.createTemplate(html);
tpl.append('blog-roll', {
    id: 'link1',
    url: 'http://www.jackslocum.com/',
    text: "Jack's Site"
});
tpl.append('blog-roll', {
    id: 'link2',
    url: 'http://www.dustindiaz.com/',
    text: "Dustin's Site"
});
 *

* *

Compiling Templates

Templates are applied using regular expressions. The performance is great, but if * you are adding a bunch of DOM elements using the same template, you can increase * performance even further by {@link Ext.Template#compile "compiling"} the template. * The way "{@link Ext.Template#compile compile()}" works is the template is parsed and * broken up at the different variable points and a dynamic function is created and eval'ed. * The generated function performs string concatenation of these parts and the passed * variables instead of using regular expressions. *


var html = '{text}';

var tpl = new Ext.DomHelper.createTemplate(html);
tpl.compile();

//... use template like normal
 *

* *

Performance Boost

DomHelper will transparently create HTML fragments when it can. Using HTML fragments instead * of DOM can significantly boost performance.

Element creation specification parameters may also be strings. If {@link #useDom} is false, * then the string is used as innerHTML. If {@link #useDom} is true, a string specification * results in the creation of a text node. Usage:


Ext.DomHelper.useDom = true; // force it to use DOM; reduces performance
 *

* @singleton */ Ext.DomHelper = function(){ var tempTableEl = null, emptyTags = /^(?:br|frame|hr|img|input|link|meta|range|spacer|wbr|area|param|col)$/i, tableRe = /^table|tbody|tr|td$/i, pub, // kill repeat to save bytes afterbegin = "afterbegin", afterend = "afterend", beforebegin = "beforebegin", beforeend = "beforeend", ts = '', te = '

', tbs = ts+'', tbe = ''+te, trs = tbs + '', tre = ''+tbe; // private function doInsert(el, o, returnElement, pos, sibling, append){ var newNode = pub.insertHtml(pos, Ext.getDom(el), createHtml(o)); return returnElement ? Ext.get(newNode, true) : newNode; } // build as innerHTML where available function createHtml(o){ var b = "", attr, val, key, keyVal, cn; if(typeof o == 'string'){ b = o; } else if (Ext.isArray(o)) { Ext.each(o, function(v) { b += createHtml(v); }); } else { b += "<" + (o.tag = o.tag || "div"); Ext.iterate(o, function(attr, val){ if(!/tag|children|cn|html$/i.test(attr)){ if (Ext.isObject(val)) { b += " " + attr + "='"; Ext.iterate(val, function(key, keyVal){ b += key + ":" + keyVal + ";"; }); b += "'"; }else{ b += " " + ({cls : "class", htmlFor : "for"}[attr] || attr) + "='" + val + "'"; } } }); // Now either just close the tag or try to add children and close the tag. if (emptyTags.test(o.tag)) { b += "/>"; } else { b += ">"; if ((cn = o.children || o.cn)) { b += createHtml(cn); } else if(o.html){ b += o.html; } b += ""; } } return b; } function ieTable(depth, s, h, e){ tempTableEl.innerHTML = [s, h, e].join(''); var i = -1, el = tempTableEl; while(++i < depth){ el = el.firstChild; } return el; } /** * @ignore * Nasty code for IE's broken table implementation */ function insertIntoTable(tag, where, el, html) { var node, before; tempTableEl = tempTableEl || document.createElement('div'); if(tag == 'td' && (where == afterbegin || where == beforeend) || !/td|tr|tbody/i.test(tag) && (where == beforebegin || where == afterend)) { return; } before = where == beforebegin ? el : where == afterend ? el.nextSibling : where == afterbegin ? el.firstChild : null; if (where == beforebegin || where == afterend) { el = el.parentNode; } if (tag == 'td' || (tag == "tr" && (where == beforeend || where == afterbegin))) { node = ieTable(4, trs, html, tre); } else if ((tag == "tbody" && (where == beforeend || where == afterbegin)) || (tag == "tr" && (where == beforebegin || where == afterend))) { node = ieTable(3, tbs, html, tbe); } else { node = ieTable(2, ts, html, te); } el.insertBefore(node, before); return node; } pub = { /** * Returns the markup for the passed Element(s) config. * @param {Object} o The DOM object spec (and children) * @return {String} */ markup : function(o){ return createHtml(o); }, /** * Inserts an HTML fragment into the DOM. * @param {String} where Where to insert the html in relation to el - beforeBegin, afterBegin, beforeEnd, afterEnd. * @param {HTMLElement} el The context element * @param {String} html The HTML fragmenet * @return {HTMLElement} The new node */ insertHtml : function(where, el, html){ var hash = {}, hashVal, setStart, range, frag, rangeEl, rs; where = where.toLowerCase(); // add these here because they are used in both branches of the condition. hash[beforebegin] = ['BeforeBegin', 'previousSibling']; hash[afterend] = ['AfterEnd', 'nextSibling']; if (el.insertAdjacentHTML) { if(tableRe.test(el.tagName) && (rs = insertIntoTable(el.tagName.toLowerCase(), where, el, html))){ return rs; } // add these two to the hash. hash[afterbegin] = ['AfterBegin', 'firstChild']; hash[beforeend] = ['BeforeEnd', 'lastChild']; if ((hashVal = hash[where])) { el.insertAdjacentHTML(hashVal[0], html); return el[hashVal[1]]; } } else { range = el.ownerDocument.createRange(); setStart = "setStart" + (/end/i.test(where) ? "After" : "Before"); if (hash[where]) { range[setStart](el); frag = range.createContextualFragment(html); el.parentNode.insertBefore(frag, where == beforebegin ? el : el.nextSibling); return el[(where == beforebegin ? "previous" : "next") + "Sibling"]; } else { rangeEl = (where == afterbegin ? "first" : "last") + "Child"; if (el.firstChild) { range[setStart](el[rangeEl]); frag = range.createContextualFragment(html); if(where == afterbegin){ el.insertBefore(frag, el.firstChild); }else{ el.appendChild(frag); } } else { el.innerHTML = html; } return el[rangeEl]; } } throw 'Illegal insertion point -> "' + where + '"'; }, /** * Creates new DOM element(s) and inserts them before el. * @param {Mixed} el The context element * @param {Object/String} o The DOM object spec (and children) or raw HTML blob * @param {Boolean} returnElement (optional) true to return a Ext.Element * @return {HTMLElement/Ext.Element} The new node */ insertBefore : function(el, o, returnElement){ return doInsert(el, o, returnElement, beforebegin); }, /** * Creates new DOM element(s) and inserts them after el. * @param {Mixed} el The context element * @param {Object} o The DOM object spec (and children) * @param {Boolean} returnElement (optional) true to return a Ext.Element * @return {HTMLElement/Ext.Element} The new node */ insertAfter : function(el, o, returnElement){ return doInsert(el, o, returnElement, afterend, "nextSibling"); }, /** * Creates new DOM element(s) and inserts them as the first child of el. * @param {Mixed} el The context element * @param {Object/String} o The DOM object spec (and children) or raw HTML blob * @param {Boolean} returnElement (optional) true to return a Ext.Element * @return {HTMLElement/Ext.Element} The new node */ insertFirst : function(el, o, returnElement){ return doInsert(el, o, returnElement, afterbegin, "firstChild"); }, /** * Creates new DOM element(s) and appends them to el. * @param {Mixed} el The context element * @param {Object/String} o The DOM object spec (and children) or raw HTML blob * @param {Boolean} returnElement (optional) true to return a Ext.Element * @return {HTMLElement/Ext.Element} The new node */ append : function(el, o, returnElement){ return doInsert(el, o, returnElement, beforeend, "", true); }, /** * Creates new DOM element(s) and overwrites the contents of el with them. * @param {Mixed} el The context element * @param {Object/String} o The DOM object spec (and children) or raw HTML blob * @param {Boolean} returnElement (optional) true to return a Ext.Element * @return {HTMLElement/Ext.Element} The new node */ overwrite : function(el, o, returnElement){ el = Ext.getDom(el); el.innerHTML = createHtml(o); return returnElement ? Ext.get(el.firstChild) : el.firstChild; }, createHtml : createHtml }; return pub; }();