Use the Ternary Operator for Conditionals in Vue

You can use the ternary operator ? in Vue templates to conditionally display data. The ternary operator works with {{}}, v-text, :show, :class, :style, and other render-only directives. However, you cannot use the ternary operator with v-model.

Vue.createApp({
  data: () => ({ value: 0 }),
  methods: {
    increaseVal() {
      this.value++;
    }
  },
  template: `
  <div>
    <div>
      <button @click="increaseVal">Increase Value by 1</button>
    </div>
    <div>Current Value: {{value}}</div>
    <div :style="{ color: value % 2 === 0 ? 'red' : 'green' }">
      {{value % 2 == 0 ? 'Value is even' : 'Value is odd'}}
    </div>
  </div>
  `
});

With v-model

You cannot use the ternary operator ? with v-model expressions. However, remember that two way data binding with v-model is just a combination of v-bind and v-on:input. So if you want to update a different variable based on a condition, you can implement v-model manually as follows.

Vue.createApp({
  // If `disableBinding` is true, updating the text input will not
  // modify `value`
  data: () => ({ disableBinding: false, value: 'Hello, World!' }),
  template: `
  <div>
    <div>
      <div>Text Input:</div>
      <input
        :value="value"
        @change="value = disableBinding ? value : $event.target.value">
    </div>
    <div>
      <div>JS Value:</div>
      <div>{{value}}</div>
    </div>
    <div>
      <div>Disable Binding</div>
      <input type="checkbox" v-model="disableBinding">
    </div>
  </div>
  `
}).mount('#app2');

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