title: How to trigger a vue method only once, not every time
body: <p>I'm handling a rotate even on <code>change</code>:</p>
  
  <pre><code>&lt;div @change="handleRotate"&gt;&lt;/div&gt;
  &lt;script&gt;
  export default {
    data: {
      rotate = 0
    },
    methods: {
      handleRotate () {
        this.rotate = this.rotate + this.getRotateAngle(e.clientX, e.clientY)
      }
    }
  }
  &lt;/script&gt;
  </code></pre>
  
  <p>Right now, the second <code>this.rotate</code> runs on every <code>change</code>. How can I do it so that the second <code>this.rotate</code> is applied only the first time <code>handleRotate</code> runs?</p>