ember-composable-helpers

Composable helpers for Ember that enables more declarative templating. These helpers can be composed together to form powerful ideas:

{{#each (map-by "fullName" users) as |fullName|}}
  <input type="text" value={{fullName}} onchange={{action (mut newName)}}>
  <button {{action (pipe updateFullName saveUser) newName}}>
    Update and save {{fullName}} to {{newName}}
  </button>
{{/each}}

To install:

ember install ember-composable-helpers

Watch a free video overview presented by EmberMap:

Configuration

This addon performs optional tree-shaking – you can specify which helpers to whitelist or blacklist using only or except within your config/environment.js:

module.exports = function(environment) {
  var ENV = {
    'ember-composable-helpers': {
      only: ['inc', 'dec', 'pipe'],
      except: ['pipe', 'filter-by']
    }
  };

Both only and except can be safely used together (the addon computes the diff), although it's best if you only use one for your own sanity.

except: ['pipe'] // imports all helpers except `pipe`
only: ['pipe'] // imports only `pipe`

Argument ordering

This addon is built with composability in mind, and in order to faciliate that, the ordering of arguments is somewhat different then you might be used to.

For all non-unary helpers, the subject of the helper function will always be the last argument. This way the arguments are better readable if you compose together multiple helpers:

{{take 5 (sort "lastName" "firstName" (filter-by "active" array))}}

For action helpers, this will mean better currying semantics:

<button {{action (pipe (action "closePopover") (toggle "isExpanded")) this}}>
  {{if isExpanded "I am expanded" "I am not"}}
</button>

Available helpers

• Action
  • pipe
  • compute
  • toggle
  • optional
• String
  • camelize
  • capitalize
  • classify
  • dasherize
  • truncate
  • underscore
  • w
• Array
  • map-by
  • sort-by
  • filter-by
  • reject-by
  • find-by
  • intersect
  • invoke
  • union
  • take
  • drop
  • repeat
  • reverse
  • range
  • join
  • compact
  • contains
  • append
  • chunk
  • without
  • array
  • shuffle
  • flatten
  • object-at
• Object
  • group-by
• Math
  • inc
  • dec

Usage

Action helpers

pipe

Pipes the return values of actions in a sequence of actions. This is useful to compose a pipeline of actions, so each action can do only one thing.

<button {{action (pipe addToCart purchase redirectToThankYouPage) item}}>
  1-Click Buy
</button>

The pipe helper is Promise-aware, meaning that if any action in the pipeline returns a Promise, its return value will be piped into the next action. If the Promise rejects, the rest of the pipeline will be aborted.

The pipe helper can also be used directly as a closure action (using pipe-action) when being passed into a Component, which provides an elegant syntax for composing actions:

{{foo-bar
    addAndSquare=(pipe-action (action "add") (action "square"))
    multiplyAndSquare=(pipe-action (action "multiply") (action "square"))
}}

{{! foo-bar/template.hbs }}
<button {{action addAndSquare 2 4}}>Add and Square</button>
<button {{action multiplyAndSquare 2 4}}>Multiply and Square</button>

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compute

Calls an action as a template helper.

The square of 4 is {{compute (action "square") 4}}

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toggle

Toggles a boolean value.

<button {{action (toggle "isExpanded" this)}}>
  {{if isExpanded "I am expanded" "I am not"}}
</button>

toggle can also be used directly as a closure action using toggle-action:

{{foo-bar
    toggleIsExpanded=(toggle-action "isExpanded" this)
    toggleIsSelected=(toggle-action "isSelected" this)
}}

{{! foo-bar/template.hbs }}
<button {{action toggleIsExpanded}}>Open / Close</button>
<button {{action toggleIsSelected}}>Select / Deselect</button>

toggle also accepts optional values to rotate through:

<button {{action (toggle "currentName" this "foo" "bar" "baz")}}>
  {{currentName}}
</button>

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optional

Allows for the passed in action to not exist.

<button {{action (optional handleClick)}}>Click Me</button>

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---

String helpers

camelize

Camelizes a string using Ember.String.camelize.

{{camelize "hello jim bob"}}
{{camelize stringWithDashes}}

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capitalize

Capitalizes a string using Ember.String.capitalize.

{{capitalize "hello jim bob"}}
{{capitalize fullName}}

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classify

Classifies a string using Ember.String.classify.

{{classify "hello jim bob"}}
{{classify stringWithDashes}}

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dasherize

Capitalizes a string using Ember.String.dasherize.

{{dasherize "whatsThat"}}
{{dasherize phrase}}

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truncate

Truncates a string with a characterLimit.

{{truncate "Lorem ipsum dolor sit amet, consectetur adipiscing elit." 20}}
{{truncate phrase}}

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underscore

Capitalizes a string using Ember.String.underscore.

{{underscore "whatsThat"}}
{{underscore phrase}}

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w

Splits a string on whitespace and/or turns multiple words into an array

{{#each (w "First" "Second" "Last") as |rank|}}
  Our {{rank}} place winner is ...
{{/each}}

or:

{{#each (w "First Second Last") as |rank|}}
  Our {{rank}} place winner is ...
{{/each}}

See also: Ember w documentation

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---

Array helpers

map-by

Maps an array on a property.

{{#each (map-by "fullName" users) as |fullName|}}
  {{fullName}}
{{/each}}

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sort-by

Sort an array by given properties.

{{#each (sort-by "lastName" "firstName" users) as |user|}}
  {{user.lastName}}, {{user.firstName}}
{{/each}}

You can append :desc to properties to sort in reverse order.

{{#each (sort-by "age:desc" users) as |user|}}
  {{user.firstName}} {{user.lastName}} ({{user.age}})
{{/each}}

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filter-by

Filters an array by a property.

{{#each (filter-by "isActive" true users) as |user|}}
  {{user.name}} is active!
{{/each}}

If you omit the second argument it will test if the property is truthy.

{{#each (filter-by "address" users) as |user|}}
  {{user.name}} has an address specified!
{{/each}}

You can also pass an action as second argument:

{{#each (filter-by "age" (action "olderThan" 18) users) as |user|}}
  {{user.name}} is older than eighteen!
{{/each}}

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reject-by

The inverse of filter by.

{{#each (reject-by "isActive" true users) as |user|}}
  {{user.name}} is not active!
{{/each}}

If you omit the third argument it will test if the property is falsey.

{{#each (reject-by "address" users) as |user|}}
  {{user.name}} does not have an address specified!
{{/each}}

You can also pass an action as third argument:

{{#each (reject-by "age" (action "youngerThan" 18) users) as |user|}}
  {{user.name}} is older than eighteen!
{{/each}}

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find-by

Returns the first entry matching the given value.

{{#with (find-by 'name' lookupName people) as |person|}}
  {{#if person}}
    {{#link-to 'person' person}}
      Click here to see {{person.name}}'s details
    {{/link-to}}
  {{/if}}
{{/with}}

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intersect

Creates an array of unique values that are included in all given arrays.

<h1>Matching skills</h1>
{{#each (intersect desiredSkills currentSkills) as |skill|}}
  {{skill.name}}
{{/each}}

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invoke

Invokes a method on an object, or on each object of an array.

<div id="popup">
  {{#each people as |person|}}
    <button {{action (invoke "rollbackAttributes")}}>
      Undo
    </button>
  {{/each}}
  <a {{action (invoke "save" people)}}>Save</a>
</div>

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union

Joins arrays to create an array of unique values. When applied to a single array, has the same behavior as uniq.

{{#each (union cartA cartB cartC) as |cartItem|}}
  {{cartItem.price}} x {{cartItem.quantity}} for {{cartItem.name}}
{{/each}}

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take

Returns the first n entries of a given array.

<h3>Top 3:</h3>
{{#each (take 3 contestants) as |contestant|}}
  {{contestant.rank}}. {{contestant.name}}
{{/each}}

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drop

Returns an array with the first n entries omitted.

<h3>Other contestants:</h3>
{{#each (drop 3 contestants) as |contestant|}}
  {{contestant.rank}}. {{contestant.name}}
{{/each}}

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repeat

Repeats n times. This can be useful for making an n-length arbitrary list for iterating upon (you can think of this form as a times helper, a la Ruby's 5.times { ... }):

{{#each (repeat 3) as |empty|}}
  I will be rendered 3 times
{{/each}}

You can also give it a value to repeat:

{{#each (repeat 3 "Adam") as |name|}}
  {{name}}
{{/each}}

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reverse

Reverses the order of the array.

{{#each (reverse friends) as |friend|}}
  If {{friend}} was first, they are now last.
{{/each}}

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range

Generates a range of numbers between a min and max value.

{{#each (range 10 20) as |number|}}
  {{! `number` will go from 10 to 19}}
{{/each}}

It can also be set to inclusive:

{{#each (range 10 20 true) as |number|}}
  {{! `number` will go from 10 to 20}}
{{/each}}

And works with a negative range:

{{#each (range 20 10) as |number|}}
  {{! `number` will go from 20 to 11}}
{{/each}}

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join

Joins the given array with an optional separator into a string.

{{join ', ' categories}}

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compact

Removes blank items from an array.

{{#each (compact arrayWithBlanks) as |notBlank|}}
  {{notBlank}} is most definitely not blank!
{{/each}}

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contains

Checks if a given value or sub-array is contained within an array.

{{contains selectedItem items}}
{{contains 1234 items}}
{{contains "First" (w "First Second Third") }}
{{contains (w "First Second") (w "First Second Third")}}

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append

Appends the given arrays and/or values into a single flat array.

{{#each (append catNames dogName) as |petName|}}
  {{petName}}
{{/each}}

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chunk

Returns the given array split into sub-arrays the length of the given value.

{{#each (chunk 7 daysInMonth) as |week|}}
  {{#each week as |day|}}
    {{day}}
  {{/each}}
{{/each}}

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without

Returns the given array without the given item(s).

{{#each (without selectedItem items) as |remainingItem|}}
  {{remainingItem.name}}
{{/each}}

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array

Similar to the hash helper, this lets you compose arrays directly in the template:

{{#each (array 1 2 3) as |numbers|}}
  {{numbers}}
{{/each}}

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shuffle

Shuffles an array with a randomizer function, or with Math.random as a default. Your randomizer function should return a number between 0 and 1.

{{#each (shuffle array) as |value|}}
  {{value}}
{{/each}}

{{#each (shuffle (action "myRandomizer") array) as |value|}}
  {{value}}
{{/each}}

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flatten

Flattens an array to a single dimension.

{{#each (flatten anArrayOfNamesWithMultipleDimensions) as |name|}}
  Name: {{name}}
{{/each}}

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object-at

Returns the object at the given index of an array.

{{object-at index array}}

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---

Object helpers

group-by

Returns an object where the keys are the unique values of the given property, and the values are an array with all items of the array that have the same value of that property.

{{#each-in (group-by "category" artists) as |category artists|}}
  <h3>{{category}}</h3>
  <ul>
    {{#each artists as |artist|}}
      <li>{{artist.name}}</li>
    {{/each}}
  </ul>
{{/each-in}}

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---

Math helpers

inc

Increments by 1 or step.

{{inc numberOfPeople}}
{{inc 2 numberOfPeople}}

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dec

Decrements by 1 or step.

{{dec numberOfPeople}}
{{dec 2 numberOfPeople}}

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See also:

• ember-truth-helpers

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Licensed under the MIT license