Template Engine

3 Jul 20235 minutes to read

Syncfusion JavaScript (Essential JS 2) has built-in template engine which provides options to compile template string into a executable function. Then the generated executable function can be used for rendering DOM element using desired data.

Compiling

compile method from ej2-base can be used to convert our template strings into executable functions.

index.js
index.html
// data
var data = { name: 'Aston Martin' };

// Compiling template string into executable function
var getDOMString = ej.base.compile('<div>${name}</div>');

// Using generated function to get output element collection
var output = getDOMString(data);

// append html collection to element
document.getElementById('element').appendChild(output[0]);
<!DOCTYPE html><html lang="en"><head>
    <title>Animation</title>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta name="author" content="Syncfusion">
    <link href="index.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/28.1.33/ej2-base/styles/material.css" rel="stylesheet">
    
    
<script src="https://cdn.syncfusion.com/ej2/28.1.33/dist/ej2.min.js" type="text/javascript"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    
    <div id="container">
        <div id="element"></div>
    </div>


<script>
var ele = document.getElementById('container');
if(ele) {
  ele.style.visibility = "visible";
}   
      </script>
<script src="index.js" type="text/javascript"></script>
</body></html>

To enable strict Content Security Policy (CSP), it is recommended to utilize the function template approach instead of the string template.

Available template syntax

Name	Syntax	Description
Expression	`<div>${name}</div>`	We have expression evolution as like ES6 expression string literals.
Dot Variable Access	`<div>${person.info.name}</div>`	Access the json variable with dot notation.
Variable Function	`<div>${name.toUpperCase()}</div>`	Utilize the variable function example, `name.toUpperCase()`
Window Function	`<div>${getCurrentTime()}div>`	Use window function inside template.Note: Here, `getCurrentTime()` is a function that defined in the window object.
Custom Helper Function	`<div>${covertToCurrency()}div>`	Use function that passed in helper function.
IF Else Statement	`<div>` `${if(gender===”male”)}` `<span class=’ico-male’>Male</span>` `${else}` `<span class=’ico-female’>Female</span>` `${/if}` `</div>`	Branching statement in Template.
For Statement	`<div>` `${for(mark of marks)}` `<span>${mark}</span>` `${/for}` `</div>`	Use for looping inside template.
For Index value access	`<div>` `${for(mark of marks)}` `<span>${markIndex}</span>` `${/for}` `</div>`	Get the index value of item while using for statement. Use the variable `Index` that suffixed with loop item name.

Custom helper

Custom helper function can be defined and passed to compile function. Refer to the following example.

index.js
index.html
var customHelper = {
    upperCase: function upperCase(str) {
        return str.toUpperCase();
    }
};

var data = { name: 'Aston Martin' };

var getDOMString = ej.base.compile('<div>${upperCase(name)}</div>', customHelper);

let opElem = getDOMString(data);

document.getElementById('element').appendChild(opElem[0]);
<!DOCTYPE html><html lang="en"><head>
    <title>Animation</title>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta name="author" content="Syncfusion">
    <link href="index.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/28.1.33/ej2-base/styles/material.css" rel="stylesheet">
    
    
<script src="https://cdn.syncfusion.com/ej2/28.1.33/dist/ej2.min.js" type="text/javascript"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    
    <div id="container">
        <div id="element"></div>
    </div>


<script>
var ele = document.getElementById('container');
if(ele) {
  ele.style.visibility = "visible";
}   
      </script>
<script src="index.js" type="text/javascript"></script>
</body></html>