Handlebars in Monster-UI

In order to add dynamic data in our views, we needed a templating engine. And Handlebars is the templating engine we chose. In this document, we'll explain how to use it, and how to use some helpers that can be very helpful for certain tasks.

How to use it

Let's start with an easy example. We want to display a banner displaying Hello Georges! whenever the User georges logs in. The HTML to do that could be something like this:


<div class="banner-hello">
    <span>Hello Georges!</span>

This hello.html file is a template. In order to add it somewhere in your UI, you would do container.append(monster.template(self, 'hello')) and it would add this HTML inside the container.

Now let's add some dynamic data, since that's why we need to use Handlebars in the first place! The problem with our template above, is that we need to say Hello to the user, and we don't want to display Hello Georges! but Hello followed by the first name of the user. In order to do so, we need to have a variable inside this template. We know that in order to give a variable to our template we need to do:


var dataTemplate = {
        firstName: 'Pedro'
    template = monster.template(self, 'hello', dataTemplate);


<div class="banner-hello">
    <span>Hello {{firstName}}!</span>

It's almost exactly the same template as above, except that we're now using the firstName variable, and we can now dislpay it properly for all the users.

Going further

First of all, we require all the templates to be internationalizable. We don't force you to create more than the en-US.json file, but it's important to have the capability to add more languages later on. If you want a better understanding on how to use the i18n, please go visit this link

Listing of different helpers

Handlebars comes with a lot of helpers already built, you can see the list here. It includes basic helpers such as each, if, unless, etc...

Now we'll check which helpers we created to help us specifically with some common problems we encountered.


The debug helper is really helpful to debug your templates. Sometimes you lose track of the current context in the template, and dropping a {{debug}} will output the current context in the console. You can also add an argument after it to output a specific object. Here's an example:


{{debug}} <!-- Would output the entire context, containing users and anything else -->
{{debug users}} <!-- Would output the entire users object}} -->
{{each users}}
    {{debug}} <!-- Would output the object representing the current user -->
    <div class="user-div">
        <span class="user-first-name">{{firstName}}</span>
        <span class="user-last-name">{{lastName}}</span>

The formatPhoneNumber helper can display a phone-number with proper formatting automatically. It's useful because a lot of numbers are stored in the database with a format such as +14151993821 and we want to display them to the user like +1 (415) 199-3821.


<div class="user-div">
    <span class="user-first-name">{{firstName}}</span>
    <span class="user-last-name">{{lastName}}</span>

    <div class="user-phone-number">{{formatPhoneNumber phoneNumber}}</div>

This helper is pretty simple, and is basically executing the toLowerCase() JS function, to a string in a template. For example it would transform Giorgio in giorgio.


<div class="user-div">
    <span class="small-user-first-name">{{toLowerCase firstName}}</span>

There is no way natively in Handlebars to compare if a string is equals to "test2" for example. Although it makes sense to try and avoid doing logic in the views, there are some places where we need this logic in the view instead of adding tons of code in the JS. The compare helper is here to help us with it.

In order to use it, you need to give 3 arguments: the left value, the operator, needs to be in this list: ['==', '===', '!=', '!==', '<', '>', '<=', '>=', 'typeof'], * the right value

Let's see an example:


{{compare role "===" "admin"}}
    <div class="admin-welcome">You're an admin! You must be so cool!</div>
    <div class="peon-welcome">You're a user! That's cool.</div>

In the above example, we check if the role of a user is "admin" and if it is we display a special div, otherwise we display another one. We can use it the same way to compare values, for example {{compare moneyLeft ">=" 10000}}You're so rich...{{/compare}}. You get the idea!


This helper allows you to replace a variable inside another variable with Handlebars. It's useful for i18n keys. You can see a very good example about this helper here.


This helper allows you to display time in a customizable format. It take a mandatory Gregorian timestamp in parameter and returns a formatted date:

{{toFriendlyDate gregorianTimestamp}}

Output: 12/01/14 12:43PM

If you want to display a time in another format, you can specify an optional parameter:

{{toFriendlyDate gregorianTimestamp 'DD-MM-year hh:mm:ss12h'}}

Output: 12-01-2014 12:43:23PM

In bonus, you can set the optional parameter to short to simply display the date:

{{tofriendlyDate gregorianTimestamp 'short'}}

Output: 12/01/2014

This helper will search for the following strings and replace them by the corresponding values: year: full year YY: last 2 digits of the year month: month of the year in letters MM: month as a 2 digits number day: day of the week in letters DD: date of the day hh: hours mm: minutes ss: seconds 12h: use the 12h format (if not specified, the 24h format is used)


The formatPrice helper can display a price with the proper amount of decimals. It's useful because prices can have a various number of decimals, but should be displayed in a consistent way. The example below will round off the price to two (2) decimals, and display it with two (2) decimals even if it has less than that (i.e. "6" -> "6.00", "6.666" -> "6.67").


<div class="item-row">
    <span class="item-name">{{name}}</span>
    <span class="item-price">{{formatPrice price 2}}</span>

This helper allows you to generate a switch from a simple checkbox.

    <input type="checkbox" />

Any property (class, id, checked, data-something ,etc...) set on the input will be conserved.


This helper allows you to generate a pretty checkbox from a simple checkbox input.

    <input type="checkbox" />

Any property (class, id, checked, data-something ,etc...) set on the input will be conserved. You can also provide parameters to define a label, set its positioning, and set the size of the checkbox. All optional.

{{#monsterCheckbox "large-checkbox" "prepend-label" "My Checkbox's label"}}
    <input type="checkbox" />

This helper allows you to generate a wrapper around your text, with a pre-set design used in many different places in the Monster-UI, so it looks consistent with the rest of the UI.

First argument is optional and defaults to 'info'. Choices are 'info', 'question', 'error', 'warning'. Error will display a wrapper of the red color, Warning will display a wrapper of the yellow color, and question will show a question mark instead of the standard info icon.

Second argument is optional and let you define a className that will be added to the main wrapper so you can apply some CSS rules to it.

{{#monsterText}} Monster is <h3>awesome</h3> {{/monsterText}}
{{#monsterText 'error'}} Monster is <strong>NOT</strong> awesome {{/monsterText}}
{{#monsterText 'warning' 'myClassName'}} Monster could be awesome {{/monsterText}}
{{#monsterText 'question'}} Is Monster Awesome?{{/monsterText}}

Similar to monsterCheckbox, this helper allows you to generate a pretty radio button from a simple radio input.

    <input type="radio" name="myRadioName" />

Any property (class, id, checked, data-something ,etc...) set on the input will be conserved. You can also provide parameters to define a label, set its positioning, and set the size of the radio. All optional.

{{#monsterRadio "large-radio" "prepend-label" "My Radio Button's label"}}
    <input type="radio" name="myRadioName" />

If you want to display data from the back-end, often times you'll try to parse the text and have a better text displayed instead. But what if the back-end moves faster and add more keys? You still want to be able to display text for that key. This is what tryI18n is for. Basically, it will check if a key has a translation in a JSON object. If it has one, it will display the friendly text, if not, it will display the variable name!

Let's say we have a i18n file like:

    "demoHandlebars": {
        "test_1": "Test 1",
        "test_2": "Test 2",
        "test_3": "Test 3"

and a HTML template named 'templateName' like:

{{#each keys}}
    {{ tryI18n i18n.demoHandlebars this }}<br/>

And we use this in JS:

var obj = { keys: ['test_1','test_2','test_3'] };

monster.template(self, 'templateName', obj);

The final output would be something like

Test 1

Test 2

Test 3

This helper will check if an array contains a specific value and display the related HTML.


<input type="checkbox"{{#ifInArray 'VP8' media.video.codecs}} checked="checked"{{/ifInArray}} value="{{codec}}"/>

Here we tick the checkbox depending on the 'VP8' video codec being in the list of available codecs.

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