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Secret of Javascript Templating
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<!DOCTYPE html> | |
<html lang="en"> | |
<head> | |
<title></title> | |
<meta charset="UTF-8"> | |
<meta name="viewport" content="width=device-width, initial-scale=1"> | |
</head> | |
<body> | |
<div id="root"> | |
<div>{{ Title }}</div> | |
<div> | |
<div data-title="{{Title}}">{{Title}} has {{Heroes.length}} Heroes</div> | |
</div> | |
</div> | |
<fieldset style="border: 1px silid #eee;"> | |
<legend>Developer Control Panel</legend> | |
<div> | |
<button onclick="renderAgainWithNewHero()">Render With New Hero</button> | |
</div> | |
</fieldset> | |
<script> | |
//JS templating | |
//converting data to view with html template | |
var viewEngine = (() => { | |
class Engine { | |
compilePlaceHolders(templateStr, scope) { | |
//finding the template placeholders '{{xxxx}}' and loop each and every occurance | |
return templateStr.replace(/\{{([^{}]*)}}/g, (a, b) => { | |
var expr = b.replace(/ /g, ''), | |
val = scope[expr]; | |
//condition to handle "Heroes.length" kind of usage | |
if (b.indexOf('.') > 0) { | |
var exprlst = b.split('.'), | |
resultedVal = scope; | |
exprlst.forEach((g) => { | |
//checking is value exists in scope property | |
//i.e., app["Heroes"] and again Heroes["length"] | |
if (resultedVal[g]) { | |
resultedVal = resultedVal[g]; | |
} | |
}); | |
val = resultedVal; | |
} | |
return val ? val : ''; | |
}); | |
} | |
render(appData, rootSelector) { | |
var rootElem = document.querySelector(rootSelector); | |
if (rootElem) { | |
//looping through childNodes to replace template placeholders | |
document.querySelector('#root').childNodes.forEach((n) => { | |
if (!n.template) { | |
//Storing text as template, it can be used to replace later | |
n.template = n.textContent; | |
}; | |
n.textContent = this.compilePlaceHolders(n.template, appData) | |
}); | |
} | |
} | |
} | |
return new Engine(); | |
})(); | |
var app = { | |
Title: 'Flash', | |
Heroes: [ | |
{ | |
Name: 'Flash' | |
}, | |
{ | |
Name: 'Cisco' | |
} | |
] | |
}; | |
viewEngine.render(app, '#root'); | |
var renderAgainWithNewHero = () => { | |
//Adding one more Hero to Heros | |
app.Heroes.push({ Name: 'Catilin' }); | |
//Calling view Engine to render updated data | |
viewEngine.render(app, '#root'); | |
}; | |
</script> | |
</body> | |
</html> |
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