Created
March 3, 2017 10:32
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Concept of Virtual DOM
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<!DOCTYPE html> | |
<html lang="en"> | |
<head> | |
<title>Creating Virtual DOM</title> | |
<meta charset="UTF-8"> | |
<meta name="viewport" content="width=device-width, initial-scale=1"> | |
</head> | |
<body> | |
<div id="root"></div> | |
<script> | |
//method will generate unique string that helps us to tack dom elements | |
var getTimeStamp = function () { | |
function s4() { | |
return Math.floor((1 + Math.random()) * 0x10000) | |
.toString(16) | |
.substring(1); | |
} | |
return 'U' + (new Date).getTime().toString(16) + s4() + s4(); | |
}; | |
var elemCache = {}; | |
//Binding .data() fn to DOM elements to store data related to specific element | |
HTMLElement.prototype.data = function (key, val) { | |
var elem = this, | |
timeStamp = getTimeStamp(); | |
if (!elem.N2Id) { | |
elem.N2Id = timeStamp; | |
} | |
if (!elemCache[elem.N2Id]) { | |
elemCache[elem.N2Id] = {}; | |
} | |
if (!key && !val) { | |
return elemCache[elem.N2Id]; | |
} | |
if (val) { | |
elemCache[elem.N2Id][key] = val; | |
} else { | |
return elemCache[elem.N2Id][key]; | |
} | |
}; | |
var VE = function (t, p, c) { | |
this.type = t; | |
this.props = p; | |
this.childItems = c; | |
}; | |
//comparing nodes with new and old data. | |
//updating element inner html if there is any change in content | |
var compareNode = function (nodeToUpdate, srcNodeData, destNodeData) { | |
if (typeof srcNodeData.childItems === 'string') { | |
if (srcNodeData.childItems !== destNodeData.childItems) { | |
nodeToUpdate.innerHTML = srcNodeData.childItems; | |
} | |
} | |
if (srcNodeData.childItems instanceof Array) { | |
srcNodeData.childItems.forEach((t, i) => { | |
compareNode(nodeToUpdate.childNodes[i], t, destNodeData.childItems[i]); | |
}); | |
} | |
}; | |
//declaring vDOM object | |
var vDOM = {}; | |
vDOM.render = function (elemObj, rootSelector) { | |
var elemToRender = document.querySelector(rootSelector); | |
if (elemToRender) { | |
var rootElem = document.createElement('DIV'); | |
var vDOMObj = elemObj.renderFn(); | |
if (!elemToRender.data('vDOM')) { | |
rootElem.appendChild(renderNode(vDOMObj)); | |
elemToRender.data('vDOM', vDOMObj); | |
elemToRender.innerHTML = rootElem.innerHTML; | |
} else { | |
var oldDOM = elemToRender.data('vDOM'); | |
compareNode(elemToRender.childNodes[0], vDOMObj, oldDOM); | |
} | |
} | |
}; | |
var appMod = { | |
renderFn: function () { | |
//declaring our html as VE element | |
return new VE('div', { ttt: 'test' }, [ | |
new VE('span', {}, 'This is Text Node ' + (new Date).toLocaleString()), | |
new VE('div', {}, 'This is static') | |
]); | |
} | |
}; | |
var renderNode = function (vElem) { | |
var elem = document.createElement(vElem.type); | |
if (typeof vElem.childItems === 'string') { | |
elem.innerHTML = vElem.childItems; | |
} else { | |
Object.keys(vElem.props).forEach((p) => { | |
elem.setAttribute(p, vElem.props[p]); | |
}); | |
if (vElem.childItems instanceof Array) { | |
vElem.childItems.forEach((c) => { | |
var cNode = renderNode(c); | |
elem.appendChild(cNode); | |
}); | |
} | |
} | |
return elem; | |
}; | |
var tick = function () { | |
vDOM.render(appMod, '#root'); | |
}; | |
window.onload = function () { | |
setInterval(tick, 1000); | |
}; | |
</script> | |
</body> | |
</html> |
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