Wednesday, December 11, 2013

Tutorial: HTML Templates with Mustache.js

by  on December 20, 2011 in HTML 5, JavaScript, JQuery, Mustache.js, Tutorial
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When developing modern HTML applications, you often write a lot of HTML fragments programmatically. You concatenate HTML tags and dynamic data, and insert the resulting UI markup into the DOM. Here is a random code example of this approach:
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$.each(messages.reverse(), function(index, message) {
    $('#messageList').append(
        '
  • '
    •  +
            message.userName + '
    ' +
            '+
            message.datePosted + '">
    ' +
            '
    '
     + message.messageText + '
    ');
        }
    });
    The proliferation of this kind of code throughout your application comes with some downsides. The tight coupling of UI and data logic doesn’t promote separation of concerns and reuse. It makes your application harder to write and harder to maintain.

    HTML templates address this issue by decoupling the UI definition (HTML markup) from the data. There are a number of HTML template solutions out there: jQuery Templates, Underscore.js, and Mustache.js to name a few. Mustache.js is a popular choice because of its powerful syntax and fast rendering.
    Mustache is a “logic-less” template syntax. “Logic-less” means that it doesn’t rely on procedural statements (if, else, for, etc.): Mustache templates are entirely defined with tags. Mustache is implemented in different languages: Ruby, JavaScript, Python, PHP, Perl, Objective-C, Java, .NET, Android, C++, Go, Lua, Scala, etc. Mustache.js is the JavaScript implementation.
    In this article, we take a quick tour of some of the capabilities of Mustache.js.
    To start using Mustache.js, simply add a script tag to your html file pointing to mustache.js which is available here.
    You can run all the examples below here.

    Sample 1: Basic Template

    This is a self-explanatory example. Note that:
    • Instead of being defined in a variable, the data often comes from a service call (see sample 2)
    • Instead of being defined in a variable, the template is often read from a file (see sample 3)
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    var person = {
        firstName: "Christophe",
        lastName: "Coenraets",
        blogURL: "http://coenraets.org"
    };
    var template = "

    {{firstName}} {{lastName}}

    Blog: {{blogURL}}"    ;
    var html = Mustache.to_html(template, person);
    $('#sampleArea').html(html);
    Result:

    Christophe Coenraets

    Blog: http://coenraets.org

    Sample 2: Basic Template using Ajax data

    Same as sample 1, except that we get the data from an Ajax service call.
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    $.getJSON('json/data.json', function(data) {
        var template = "

    {{firstName}} {{lastName}}

    Blog: {{blogURL}}"    ;
        var html = Mustache.to_html(template, data);
        $('#sampleArea').html(html);
    });
    Result:

    John Smith

    Blog: http://johnsmith.com

    Sample 3: Externalized Template

    Same as sample 2, except that we read the template from the main HTML file.
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    $.getJSON('json/data2.json', function(data) {
        var template = $('#personTpl').html();
        var html = Mustache.to_html(template, data);
        $('#sampleArea').html(html);
    });
    The template is defined as follows in index.html:
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    <script id="personTpl" type="text/template">
    <h1>{{firstName}} {{lastName}}</h1>
    <p>Blog URL: <a href="{{blogURL}}">{{blogURL}}</a></p>
    </script>
    Result:

    Lisa Jones


    NOTE: Sample 3 represents the way templates are being used in many dynamic Web applications:
    • You get data from an Ajax service
    • You read the template from an external file
    In the remaining of this article, we declare the data and the template in variables to keep the examples self-contained. Remember to refer to sample 3 for a traditional setup when using templates in a dynamic Web application.

    Sample 4: Enumerable Section

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    var data = {name: "John Smith", skills: ['JavaScript', 'PHP', 'Java']};
    var tpl = "{{name}} skills:
      {{#skills}}
    • {{.}}
      • {{/skills}}
    "    ;
    var html = Mustache.to_html(tpl, data);
    $('#sampleArea').html(html);
    Result:
    John Smith skills:
    • JavaScript
    • PHP
    • Java

    Sample 5: Enumerable Section with Objects

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    var data = {
        employees: [
        {   firstName: "Christophe",
            lastName: "Coenraets"},
        {   firstName: "John",
            lastName: "Smith"}
        ]};
    var template = "Employees:
      {{#employees}}"
     +
                                "
  • {{firstName}} {{lastName}}
    • "     +
                                "{{/employees}}
    ";
    var html = Mustache.to_html(template, data);
    $('#sampleArea').html(html);
    Result:
    Employees:
    • Christophe Coenraets
    • John Smith

    Sample 6: Nested Objects

    You can use the dot notation to access object properties.
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    var person = {
        firstName: "Christophe",
        lastName: "Coenraets",
        blogURL: "http://coenraets.org",
        manager : {
            firstName: "John",
            lastName: "Smith"
        }
    };
    var template = "

    {{firstName}} {{lastName}}

    {{blogURL}}
    "     +
                   "Manager: {{manager.firstName}} {{manager.lastName}}";
    var html = Mustache.to_html(template, person);
    $('#sampleArea').html(html);
    Result:

    Christophe Coenraets

    http://coenraets.org
    Manager: John Smith

    Sample 7: Dereferencing

    Same as sample 6, except that we “dereference” the manager object to make it easier to access its properties (without having to use the dot notation).
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    var person = {
        firstName: "John",
        lastName: "Smith",
        blogURL: "http://johnsmith.com",
        manager : {
            firstName: "Lisa",
            lastName: "Jones"
        }
    };
    var tpl = "

    {{firstName}} {{lastName}}

    {{blogURL}}
    "     +
              "{{#manager}}Manager: {{firstName}} {{lastName}}{{/manager}}";
    var html = Mustache.to_html(tpl, person);
    $('#sampleArea').html(html);
    Result:

    John Smith

    http://johnsmith.com
    Manager: Lisa Jones

    Sample 8: Function

    Templates can reference functions like totalPrice in this example.
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    var product = {
        name: "FooBar",
        price: 100,
        salesTax: 0.05,
        totalPrice: function() {
            return this.price + this.price * this.salesTax;
        }
    };
    var template = "Product Name: {{name}}
    Price: {{totalPrice}}"    ;
    var html = Mustache.to_html(template, product);
    $('#sampleArea').html(html);
    Result:
    Product Name: FooBar
    Price: 105

    Sample 9: Condition

    Templates can include conditional sections. Conditional sections only render if the condition evaluates to true. A conditional section begins with {{#condition}} and ends with {{/condition}}. “condition” can be a boolean value or a function returning a boolean.
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    var data = {
        employees: [
        {   firstName: "Christophe",
            lastName: "Coenraets",
            fullTime: true,
            phone: "617-123-4567"
        },
        {   firstName: "John",
            lastName: "Smith",
            fullTime: false,
            phone: "617-987-6543"
        },
        {   firstName: "Lisa",
            lastName: "Jones",
            fullTime: true,
            phone: "617-111-2323"
        },
        ]};
    var tpl = "Employees:
      {{#employees}}
    • {{firstName}} {{lastName}}"
     +
              "{{#fullTime}} {{phone}}{{/fullTime}}
    {{/employees}}";
    var html = Mustache.to_html(tpl, data);
    $('#sampleArea').html(html);
    Result:
    Employees:
    • Christophe Coenraets 617-123-4567
    • John Smith
    • Lisa Jones 617-111-2323

    Sample 10: Partials

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    var data = {
        firstName: "Christophe",
        lastName: "Coenraets",
        address: "1 Main street",
        city: "Boston",
        state: "MA",
        zip: "02106"
    };
     
    var template = "

    {{firstName}} {{lastName}}

    {{>address}}"    ;
    var partials = {address: "{{address}}
    {{city}}, {{state}} {{zip}}"    };
    var html = Mustache.to_html(template, data, partials);
    $('#sampleArea').html(html);
    Result:

    Christophe Coenraets

    1 Main street
    Boston, MA 02106

    Sample 11: Partials in Enumerable Section

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    var data = { depts: [
        {   name: "Engineering",
            employees: [
                {firstName: "Christophe", lastName: "Coenraets"},
                {firstName: "John", lastName: "Smith"}]
        },
        {   name: "Sales",
            employees: [
                {firstName: "Paula", lastName: "Taylor"},
                {firstName: "Lisa", lastName: "Jones"}]
        }]
    };
     
    var tpl = "{{#depts}}

    {{name}}

    "     +
              "
      {{#employees}}{{>employee}}{{/employees}}
    {{/depts}}"    ;
    var partials = {employee: "
  • {{firstName}} {{lastName}}
    • "    };
    var html = Mustache.to_html(tpl, data, partials);
    $('#sampleArea').html(html);
    Result:

    Engineering

    • Christophe Coenraets
    • John Smith

    Sales

    • Paula Taylor
    • Lisa Jones

    You can run all the examples here.


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