Limit with init

components.limit-each.js

import Ember from 'ember';

export default Ember.Component.extend({
  init() {
    this._super(...arguments);
    const showOnly = this.get('showOnly');
    console.log('showOnly', showOnly);
    if (showOnly && Number.isInteger( parseInt(showOnly))) {
     this.set('people', this.get('people').slice(0, parseInt(showOnly)));
  }
 }
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  model: [
    { body: 'A' },
    { body: 'B' },
    { body: 'C' },
    { body: 'D' },
    { body: 'E' },
    { body: 'F' },
    ],
  limit: 2,

  actions: {
    incLimit() {
      this.incrementProperty('limit');
    }
  }

});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<h4><a href="http://www.falsepositives.com/index.php/2016/07/20/limiting-the-number-of-elements-displayed-in-a-ember-component/">Limiting the number of elements displayed in a Ember Component</a></h4>
<br>
<br>
{{outlet}}
{{limit-each showOnly=2 people=model}}
<br>
<br>

templates.components.limit-each.hbs

{{yield}}
<ul>
{{#each people as |person|}}
<li>{{person.body}}</li>
{{/each}}

</ul>

twiddle.json

{
  "version": "0.10.1",
  "description": "Limiting the number of elements displayed in a Ember Component",
  "homepage": "http://www.falsepositives.com/index.php/2016/07/20/limiting-the-number-of-elements-displayed-in-a-ember-component/",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.6.0",
    "ember-data": "2.6.1",
    "ember-template-compiler": "2.6.0"
  },
  "addons": {}
}

as explained http://www.falsepositives.com/index.php/2016/07/20/limiting-the-number-of-elements-displayed-in-a-ember-component/