New Twiddle

controllers.application.js

import Ember from 'ember';
import { A } from '@ember/array';
import EmberObject, { computed } from '@ember/object';

export default Ember.Controller.extend({
  displayData: Ember.computed('data.@each.priority', function() {
    return this.data.sort((a, b) => a.priority - b.priority);
  }),
  data: A([
    EmberObject.create({
      priority: 1,
    	name: 'Stuff',
      description: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur.'
    }),
    EmberObject.create({
      priority: 2,
    	name: 'Thing',
      description: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur.'
    }),
    EmberObject.create({
      priority: 3,
    	name: 'Object',
      description: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur.'
    }),
    EmberObject.create({
      priority: 4,
    	name: 'Item',
      description: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur.'
    }),
    EmberObject.create({
      priority: 5,
    	name: 'Blob',
      description: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur.'
    })
  ]),
  
  actions: {
  	updatePriority(index, event) {
      const begVal = parseInt(this.data[index].priority);
      let endVal = parseInt(event.target.value) || begVal;
      if(endVal > this.data.length) {
        endVal = this.data.length;
      }
      if(endVal <= 0) {
        endVal = 1;
      }
      const delta = endVal - begVal;
      if(delta > 0) {
        this.data.forEach((obj, i) => {
          if(obj.priority > begVal && obj.priority <= endVal) {
            this.data[i].set('priority', parseInt(obj.priority) - 1);
          } 
        });
      } else if(delta < 0) {
        this.data.forEach((obj, i) => {
          if(obj.priority >= endVal && obj.priority < begVal) {
            this.data[i].set('priority', parseInt(obj.priority) + 1);
          } 
        });
      }
      if(endVal == begVal) {
        // reset if input not valid, i.e. letters, negative number, etc.
        // could also do this, but is a code smell:
        // this.data[index].notifyPropertyChange('priority');
        event.target.value = endVal;
      } else {
        this.data[index].set('priority', endVal);
      }          
		}
	}
});

styles.app.css

body {
  margin: 12px 16px;
  font-family: Courier;
  font-size: 12pt;
}

.container {
	display: grid;
  grid-template-columns: 80px 100px auto;
}

.container > * {
  margin: 10px;
  align-self: center;
  color: #808080;
}

.priority {
  text-align: center;
  align-self: center;
  border: none;
}

.name {
	justify-self: center;
  align-self: center;
}

templates.application.hbs

<h1>Example</h1>

<div class="container">
	<div class="row header priority">Priority</div>
  <div class="row header name">Name</div>
  <div class="row header">Description</div>
  {{#each displayData as | row index |}}
  <input class="priority" value={{row.priority}} onBlur={{action "updatePriority" index}} />
  <div class="name">{{row.name}}</div>
  <div>{{row.description}}</div>
  {{/each}}
</div>

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"
  }
}