title: How to add a property to ALL objects in an array (data) using Vue.js?
body: <p><strong>Background</strong>:  I have an array in data() that gets populated with objects from the backend. If the GET request retrieves 6 objects those 6 objects will update in the array.</p>
  
  <p><strong>Problem</strong>: I already understand vm.$set is needed to add properties to an object. But how do add properties to all object in the array?</p>
  
  <p>I want to change:</p>
  
  <pre><code> data() {
      return {
        expenseButton: [{key:value},{key:value},{key:value}]
           };
    }
  
  </code></pre>
  
  <p>to </p>
  
  <pre><code>data() {
      return {
        expenseButton: [{key:value, key2:value2},{key:value, key2:value2},{key:value, key2:value2}]
           };
    }
  </code></pre>
  
  <p><strong>Failed attempt</strong> which logs newValue as a property in the array instead of each object</p>
  
  <pre><code>  methods: {
      check() {
        this.$set(this.expenseButton, "newValue", this.expenseButton.newValue);
        console.log(this.expenseButton);
      }
    },
  </code></pre>
  
  <p><strong>UPDATE</strong>
  How to target all objects in an array via vm.$set so that all objects has a new property called "newValue"</p>
  
  <pre><code> data() {
      return {
        expenseButton: [{key1:value1},{key2:value2},{key3:value3}]
           };
    }
  
  </code></pre>
  
  <p>TO </p>
  
  <pre><code> data() {
      return {
        expenseButton: [{key1:value1,newValue: ''},{key2:value2, newValue: ''},{key3:value3, newValue: ''}]
           };
    }
  
  </code></pre>