Implementing Computed Properties to Optimize Code

Hello, students! Welcome to Lesson 2 of Computed Properties in Vue.js. Today, we will learn how to implement computed properties to optimize code.

How can computed properties optimize code?

Computed properties are more efficient than properties directly bound to data.

This is because computed properties are calculated only when accessed.

Properties directly bound to data, on the other hand, are calculated whenever their data changes.

For example, let’s consider the following component:

<template>
  <div>
    <p>{{ text }}</p>
  </div>
</template>

<script>
export default {
  data() {
    return {
      text: 'Hello, world!',
    };
  },
};
</script>

In this component, the text property is directly bound to data. If the text is changed, the text property will be recalculated, and the component will be re-rendered.

Now, let’s consider the following component:

<template>
  <div>
    <p>{{ textSize }}</p>
  </div>
</template>

<script>
export default {
  computed: {
    textSize() {
      return this.text.length;
    },
  },
  data() {
    return {
      text: 'Hello, world!',
    };
  },
};
</script>

In this component, the textSize property is a computed property. If the text is changed, the textSize property will not be recalculated until it is accessed. This means the component will only be re-rendered when the textSize property is accessed.

Examples of Code Optimization with Computed Properties

Here are some examples of how computed properties can be used to optimize code:

• Calculate complex properties: Computed properties can be used to calculate complex properties. This can be useful to reduce the number of times code is executed.
• Apply styles conditionally: Computed properties can be used to apply styles conditionally. This can help improve the performance of the application.
• Update data only when necessary: Computed properties can be used to update data only when necessary. This can help reduce the number of times the application is rendered.

Challenge

Here’s a challenge for you:

• Create a component that displays the size of text. Use a computed property to calculate the size of the text.

Good luck!

Tip

You can use the computed property textSize from the previous example to calculate the size of the text.

In the next topic, we will learn about watchers in Vue.js. Watchers are a way to react to data changes.

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