Disabled Button Example

components.my-form.js

import Ember from 'ember';
import { computed } from '@ember/object';

export default Ember.Component.extend({
  childInputs: null,
  init() {
    this._super(...arguments);
    this.childInputs = Ember.A([ { isValid: false }, { isValid: false } ]);
  },
  
  disableButton: computed('childInputs.@each.isValid', function() {
    let inputs = this.childInputs;
    let allInputTrue = inputs.every((i) => i.isValid === true);
    
    return !allInputTrue;
  }),
  
  actions: {
    validityChanged(idx, value) {
      this.get('childInputs').replace(idx, 1, Ember.A([ {isValid: value }]));
    }
  }
});

components.my-input.js

import Ember from 'ember';
import { computed } from '@ember/object';

export default Ember.Component.extend({
  inputValue: null,
   
  didInsertElement() {
  	this._super(...arguments);
    this.validityChanged(this.isValid);
  },
  
  isValid: computed('inputValue', function() {
    return parseInt(this.inputValue, 10) > 10;
  })
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle'
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}

<MyForm as |form|>
  <form.inputFoo />
  <form.inputBar />
</MyForm>

templates.components.my-form.hbs

<h1>My Form</h1>

<form>
  {{yield (hash
    inputFoo=(component 'my-input' validityChanged=(action "validityChanged" 0))
    inputBar=(component 'my-input' validityChanged=(action "validityChanged" 1))
  )}}
  
  <br>
  <button disabled={{disableButton}}>Submit</button>
</form>

templates.components.my-input.hbs

{{input value=inputValue placeholder="Enter a value > 10" key-up=(action validityChanged isValid)}} Is Valid: {{isValid}}

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "3.4.2"
  }
}