Compose all the things (Wicked Good Ember 2015)

Compose all the things
Mike North
Wicked Good Ember 2015

@MichaelLNorth
modernwebui.org
Modern Web UI
advertising.yahoo.com
Yahoo Ads & Data
Hi
ember-resize
ember-orientation
ember-cpm
ember-cli-materialize
…and more

@MichaelLNorth
Composability
(Mike working w/ a composable system)

//TODO
• The state of ember at yahoo
• What’s composability, and why do we care?
• 4 areas where you can compose today
• Style
• CPMs
• Components
• Tests

@MichaelLNorth
Yahoo Ads & Data
• 14 Ember Apps
• 68 Ember-focused developers
• A “flagship” app that ’s huge (70K lines JS)
• An internal collection of add ons
Ember @ Yahoo

@MichaelLNorth
Composability
• Recombinant self-
contained pieces
• Built around
established contracts
and conventions
• Promotes reuse
What do I mean?

@MichaelLNorth
Why composability?
• Leverage existing code repeatedly
• Build apps in a more expressive way (DSLs)
• Opportunities for unforeseen uses!

@MichaelLNorth
Great places to start
Style
Tests
Computed Properties
Components

@MichaelLNorth
Great places to startStyle
Declarative CSS
A
<div id=“myThing”>
...
</div>
#myThing {
float: left;
color: white;
}
B
<div class=“pull-left white-text">
...
</div>
.pull-left {
float: left;
}
.white-text {
color: white;
}

@MichaelLNorth
• Atomic CSS classes
• Expressive HTML
• Promotes consistency
Declarative CSS
<div class=“pull-left white-text">
...
</div>
.pull-left {
float: left;
}
.white-text {
color: white;
}

@MichaelLNorth
• You may have classes and/or attributes for
• Testing
• Style
• Behavior
Keep attributes & classes organized
<input class="first-name large-input”
data-autoid="first-name" />
.large-input {
font-size: 32px;
}
style
fillIn(‘input[data-autoid="first-name"]',
'Mike');
testing

@MichaelLNorth
Great places to startComputed Properties
How does a computed property work?
GET
Has cached
value?
Recalculate
No
Yes
X
Allows
caching?
Cache
X
XYes
No
ReturnX

@MichaelLNorth
How does a computed property work?
DEPENDENT CHANGED
Cache
X
I’ve
changed!
ViewProperty
obj.get(‘val’)

@MichaelLNorth
CPs can be thought of as ﬁlters
CP
r
g
b
#ff1a99
get() set()
(sometimes)
CP
r
b
g
#ff1a99

@MichaelLNorth
• Ember.computed.*
Macros make this even easier
function product(prop, coeff) {
return Ember.computed(prop, {
get() {
return this.get(prop) * coeff;
}
});
}

@MichaelLNorth
totalAmount: sum(
'subtotal',
'tipAmount',
'taxAmount',
product('discount', -1)
),
Composable CPs can be mixed and
matched
ember-cpm

@MichaelLNorth
Example

@MichaelLNorth
Great places to startComponents
• Not source of truth for state ✔
• Promotes Reuse ✔
• Recombinant ?
Components are pretty close…
ember-cli-materialize

@MichaelLNorth
Looking for this
<div class="card blue-grey darken-1">
<div class="card-content white-text">
<div class="card-title">
Wicked Good Ember
</div>
This will go in the body of the card
</div>
<div class="card-action">
<a>
<span {{action “accept”}}>Accept</span>
</a>
<a>
<span {{action “cancel”}}>Cancel</span>
</a>
</div>
</div>

@MichaelLNorth
One option - lowest common element
Wicked Good Ember
</div>
</div>
<a>
</a>
<a>
</a>
</div>
</div>
{{#wge-card}}
Wicked Good Ember
</div>
</div>
{{#wge-card-action}}
<span {{action "accept"}}>
Accept
</span>
{{/wge-card-action}}
<span {{action "cancel"}}>
Cancel
</span>
</div>
{{/wge-card}}

@MichaelLNorth
One option - lowest common element
Wicked Good Ember
</div>
</div>
<a>
</a>
<a>
</a>
</div>
</div>
{{#wge-card}}
Wicked Good Ember
</div>
</div>
<span {{action "accept"}}>
Accept
</span>
<span {{action "cancel"}}>
Cancel
</span>
</div>
{{/wge-card}}
Not Useful

@MichaelLNorth
Another option - parent does everything
Wicked Good Ember
</div>
</div>
<a>
</a>
<a>
</a>
</div>
</div>
{{#wge-card
title="Wicked Good Ember"
cardActions=myCardActions}}
This will go in the body
of the card
{{/wge-card}}

@MichaelLNorth
Another option - parent does everything
Wicked Good Ember
</div>
</div>
<a>
</a>
<a>
</a>
</div>
</div>
{{#wge-card
title="Wicked Good Ember"
cardActions=myCardActions}}
This will go in the body
of the card
{{/wge-card}}
Not Composable

@MichaelLNorth
The expressive option
{{#wge-card title="Wicked Good Ember"}}
<span {{action "accept"}}>Accept</span>
<span {{action "cancel"}}>Cancel</span>
{{/wge-card}}

@MichaelLNorth
{{#wge-card
title="Wicked Good Ember"}}
This will go in the
body of the card
<span {{action “accept"}}>
Accept
</span>
<span {{action “cancel”}}>
Cancel
</span>
{{/wge-card}}
Components
Content projection - ruh roh
Wicked Good Ember
</div>
</div>
<a>
</a>
<a>
</a>
</div>
</div>
4 distinct pieces of content

@MichaelLNorth
{{#wge-card
This will go in the
body of the card
Accept
</span>
Cancel
</span>
{{/wge-card}}
Components
Content projection - ruh roh
Wicked Good Ember
</div>
</div>
<a>
</a>
<a>
</a>
</div>
</div>
4 distinct pieces of content
Sub-components
project into parent
{{yield}}
Simple property binding

@MichaelLNorth
Content projection approach
{{#wge-card
This will go in the
body of the card
Accept
</span>
Cancel
</span>
{{/wge-card}}
• Child components won’t
render directly
• Parent will handle
rendering of children
• Register/unregister to
parent

@MichaelLNorth
Child
export default Ember.Component.extend({
didInsertElement() {
this.nearestWithProperty('_wgeCard')
.registerWgeAction(this);
},
willDestroyElement() {
this.nearestWithProperty('_wgeCard')
.unregisterWgeAction(this);
},
render() {} // Don't render
});
const { computed: {alias, empty} } = Ember;
classNames: ['card'],
_wgeCard: true,
_cardActions: [],
// Needed to ensure context of
// child component templates
// is the controller
parentController: alias('targetObject'),
registerWgeAction(component) {
this.get('_cardActions')
.addObject(component);
},
unregisterWgeAction(component) {
.removeObject(component);
}
});
Parent
Components

@MichaelLNorth
import Ember from 'ember';
const { computed: {alias, empty} } = Ember;
classNames: ['card'],
_wgeCard: true,
_cardActions: [],
// Needed to ensure context of
// child component templates
// is the controller
parentController: alias('targetObject'),
registerWgeAction(component) {
.addObject(component);
},
unregisterWgeAction(component) {
.removeObject(component);
}
});
Parent
<div class="card-title">{{title}}</div>
{{yield}}
</div>
{{#if _cardActions.length}}
{{#each _cardActions as |cardAction|}}
{{view Ember.View
tagName='a'
template=cardAction.template
controller=parentController}}
{{/each}}
</div>
{{/if}}
Components
Parent.hbs

@MichaelLNorth
<div class="card-title">{{title}}</div>
{{yield}}
</div>
{{#if _cardActions.length}}
{{#each _cardActions as |cardAction|}}
{{view Ember.View
tagName='a'
template=cardAction.template
controller=parentController}}
{{/each}}
</div>
{{/if}}
“Captured”
template
Needed for
actions &
bindings

@MichaelLNorth
Great places to startTests
A lot of tests are verbose and ugly
• Sensitivity to order and/or timing
• Brittle selectors to interact with the DOM
• 1 change —> break N tests

@MichaelLNorth
test(“authorized user should end up at account's search list page”, function(assert) {
server.get(`${apiHost.url}/me`, json(200, me));
server.get(`${apiHost.url}/campaigns/:id`, json(200, campaign1));
server.get(`${apiHost.url}/seats/2`, json(200, seat2));
server.get(`${apiHost.url}/seats/1`, json(200, seat1));
server.get(`${apiHost.url}/account/:id`, json(200, account1));
server.get(`${apiHost.url}/breadcrumbs`, json(200, breadcrumbs.campaign));
visit('/app/account/1/campaigns');
andThen(function() {
assert.equal(currentPath(), ‘app.account.campaign', 'Current url is search list page for campaig
assert.equal(Ember.$('.top-navbar .brand-logo .active-title').text().trim(), campaign1.campaign
assert.equal(Ember.$('.resource-tiles-container .card').length, campaigns.campaigns.length, 'On
assert.deepEqual(Ember.$('.resource-tiles-container .resource-tile:first-child .card .card-cont
['Created', 'Updated'], 'Columns are correct');
assert.equal(Ember.$('.new-campaign-button').length, 1, 'New Campaign button is on the screen')
});
});
A lot of tests are verbose and ugly

@MichaelLNorth
A wild PageObject appears
• Prime pretender
• Access to controls
• Speciﬁc asserts
fillInclick
currentURL
andThenvisit
triggerEvent
$().val()$
$().click()$().trigger()
setFirstName
clickResetButton setAge
openSettings
PageObject API
Ember Testing API
DOMSee:

@MichaelLNorth
Writing PageObjects
• Return this
• To assert or not to assert?
• Build PageObjects for components
Example
The recombinant
part!

@MichaelLNorth
Great places to startSome ﬁnal thoughts
Even more composability on the way!
• Add-ons
• Ember.Service
• Engines (TBD)
• Components ( {{yield}}, block params,
etc…)

@MichaelLNorth
Conclusion
Style
Tests
Computed Properties
Components
truenorth/wge-examples

Compose all the things (Wicked Good Ember 2015)

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