Vue component communication: using watch and computed for data monitoring

Vue component communication: using watch and computed for data monitoring

Vue.js is a popular JavaScript framework, and its core idea is componentization. In a Vue application, data needs to be transferred and communicated between different components. In this article, we will introduce how to use Vue's watch and computed to monitor and respond to data.

watch
In Vue, watch is an option that can be used to monitor changes in one or more properties and perform corresponding operations when the properties change. We can use watch in the component's options to define one or more monitors. Here is an example of using watch:

<template>
  <div>
    <p>{{ message }}</p>
    <input v-model="inputText" type="text">
  </div>
</template>

<script>
export default {
  data() {
    return {
      message: '初始值',
      inputText: '',
    };
  },
  watch: {
    inputText(newValue) {
      this.message = newValue;
    },
  },
};
</script>

In the above code, we define a watch object in the component's options and define a monitor in it. The callback function in the monitor will be called when the inputText property changes. The parameter received by the callback function is the new property value. In the callback function, we assign the new attribute value to the message attribute, so that the value of the message is synchronized with the inputText.

computed
Computed is an option in Vue, which can be used to define computed properties. A calculated property is a value calculated based on the value of other properties. When the dependent property changes, the calculated property will recalculate and return a new value. We can use computed in the component's options to define one or more computed properties. Here is an example of using computed:

<template>
  <div>
    <p>{{ message }}</p>
  <input v-model="inputText" type="text">
  </div>
</template>

<script>
export default {
  data() {
    return {
      inputText: '',
    };
  },
  computed: {
    message() {
      return this.inputText;
    },
  },
};
</script>

In the above code, we define a computed object in the component's options and define a computed property in it. The return value of the computed property will be used as the value of the message. In this example, the value of message is synchronized with inputText, and when inputText changes, message is automatically updated.

Summary
Using watch and computed allows us to easily monitor and respond to data. Watch is suitable for when we need to do some processing on attributes or perform some side effects, while computed is suitable for when we need to calculate a new value based on existing attribute values. In actual development, we can flexibly use watch and computed to implement data communication between components as needed.

The above is an introduction to using watch and computed for data monitoring. I hope it will help you understand Vue component communication. If you want to learn more about Vue, you can check the official documentation or read related books. I wish you write better Vue applications!

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