n-handlebars

Enhanced handlebars for use in next applications

Express applications

require('n-handlebars')(app, options)

Where options may have the following properties

directory: String - absolute path to the current application's working directory REQUIRED
partialsDir: Array of directories containing partials. This is concatenated to the default value of ./bower_components/
layoutsDir: String - the directory in which express-handlebars layouts are contained
defaultLayout: Name of the default layout to use. Defaults to false
helpers: Map of custom helpers to add to handlebars (see below for a list those included by default)
viewsDirectory: String - subdirectory where the application's views are stored (default /views)
limitToComponents: Array - limit the bower components partials included to just the specified components (e.g. ['n-ui'])
extname: String - file extension of handlebars templates (default: '.html')

Returns a promise which resolves when all partials in the supplied directories have been registered

To use the express-handlebars instance by itself (occassionally useful for consuming templates from bower_components outside of the context of an express app) use require('n-handlebars').standalone(options)

A handlebars instance with all next helpers, but without partials, is also exposed at require('n-handlebars').handlebars;

Client side javascript

require('n-handlebars')(options)

Where options may have the following properties

helpers: Map of custom helpers to add to handlebars (see below for a list those included by default)

Returns a handlebars instance

Other server side applications

Should you need to use handlebars with all the next helpers but without next-express use require('n-handlebars').handlebars(options), which has the same API a the client side module

THE HELPERS

Inheritance helpers

Block inheritance

This is achieved by means of two helpers:

outputBlock used in the parent template to indicate where content should be output. Can also define default content
defineBlock used in the child template to define the desired output to insert into the block

// parent.html
<header>thing</header>
{{#outputBlock 'my-block'}}default content{{/outputBlock}}
<footer>thing</footer>

// child.html
{{#defineBlock 'my-block'}}
	Mustaches to process: {{someVar}}
{{/defineBlock}}
{{> parent}}

usePartial

Allows a partial to be selected based on the value of a variable

{{{usePartial variable path='path/to/partial'}}}

If variable value is foobar then partial will be path/to/partial/foobar. Note a '>' is not required in the path and you will normally need triple mustaches

Content helpers

dateformat

Outputting date objects as strings

{{#dateformat}}{{ a date object }}{{/dateformat}} outputs an isoString
{{#dateformat "dddd, d mmmm, yyyy"}}{{ a date object }}{{/dateformat}} outputs the date formatted as 'Tuesday, 3 February, 2014'

encode

Encoding strings to be output safely in html

{{encode q mode='uriComponent'}} outputs the result of encodeURIComponent(q) ({{encode q }} will also do this)
{{encode q mode='uri'}} outputs the result of encodeURI(q)

paragraphs

Outputting some paragraphs from a larger chunk of html, zero indexed

{{{paragraphs body start=0 end=1}}} will output the first paragraph of body. Note the triple mustaches

removeImageTags

Strips all image tags from a chunk of html

{{{removeImageTags body}}} Note the triple mustaches

resize

Replaces an image url with an image service url, serving an appropriately resized image

{{#resize 200}}http://images.com/pic.jpg{{/resize}}

json

Outputs an object as json.

{{json obj}} - for use within data attributes and elsewhere in html (will convert '"' to '"' etc..)
{{{json obj}}} - for outputting the json unencoded

concat

Concatenates strings.

{{concat str1 str2}}

decodeHtmlEntities

Decodes a (very limited) safe list* of HTML entities into their respective characters (* = not &, <, >, ", ' or ``)

{{decodeHtmlEntities 'lorem ipsum dolar'}} outputs lorem ipsum dolar

Logic helpers

ifEquals

Outputs contents if a thing is equal to a value

{{#ifEquals thing 'value'}} some content {{else}} some fallback content {{/ifEquals}}

ifEqualsSome

Outputs contents if a thing is equal to at least a value from all the values enumerated

{{#ifEqualsSome thing 'value1' 'value2'}} some content {{else}} some fallback content {{/ifEqualsSome}}

unlessEquals

Outputs contents if a thing is not exactly equal to a value

{{#unlessEquals thing 'value'}} some content {{else}} some fallback content {{/unlessEquals}}

ifAll

Outputs contents if a number of things are truthy

{{#ifAll thing1 thing2 thing3}} some content {{else}} some fallback content {{/ifAll}}

ifSome

Outputs contents if at least one of a number of things is truthy

{{#ifSome thing1 thing2 thing3}} some content {{else}} some fallback content {{/ifSome}}

ifBool

Outputs contents if a complex boolean logic expression is satisfied. Uses string formatting to generate the expression

{{#ifBool thing1 thing2 "($0 && $1)"}} some content {{else}} some fallback content {{/ifBool}}

ifTypeof

Outputs contents if typeof operator on first argument equals the second argument

{{#ifTypeof object "string"}} objectis a string {{else}}object is not a string {{/ifTypeof}}

Iteration helpers

slice

Loop through a subset of items

{{#slice items limit="2" offset="4"}} some content {{/slice}}

increment

Displays @index value added to given argument (e.g. an argument of 1 will display ordinal not cardinal numbers, i.e. values start from 1 not 0).

{{#each array}}{{#increment 1}}{{@index}}{{/increment}}{{/each}}

Presenter helpers

presenter

Makes a presenter class available to the template for the current context

example

		{{#presenter presenterPath context hashArguments}} //1
			<h3>{{@myPresenter.title}}</h3> //2
			<p>{{subheader}}</p> //3
			<ol>
				{{#with @myPresenter.items}} //4
					<li><p>{{relatedTitle}}</p></li>
				{{/with}}
			</ol>
		{{/presenter}}

Instantiating the presenter presenterPath can either be a file from the root of the application, eg. ./presenters/my-presenter or if in a bower component component/presenters/my-presenter. context is the current data context - ie. @this hashArguments is any data that you want to pass to the presenter from the template, eg. size='large' widths='1,2,3' (these can only be passed as strings) Any hashArguments are added to the data context and passed to the presenter.
Retrieving data from the presenter (swap myPresenter for the camel cased file name for your presenter) @myPresenter.title will call the title function of your presenter and receive back the output of that function. This could be a text string for example.
Using current data context the current data context is still available
Using an array from the presenter existing helpers, eg. #each, #with #slice can be used with arrays passed back from the presenter.

@financial-times/n-handlebars