force update in vuejs

 update the data from child to parent

// Dynamic outputs are not changing when secondary categories list is changed. So we have to use $forceUpdate() to re-render dynamic outputs.

this.$forceUpdate();

In Vue.js, the forceUpdate() method is used to manually trigger a re-render of a component. Normally, Vue.js automatically detects changes to the component's reactive data and updates the DOM accordingly. However, there may be situations where you need to force a re-render of the component, even if the reactive data hasn't changed.

To use the forceUpdate() method, you can call it directly on the Vue component instance:

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this.$forceUpdate();

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Here's an example to illustrate the usage of forceUpdate() s

<template>
  <div>
    <p>{{ message }}</p>
    <button @click="updateMessage">Update Message</button>
  </div>
</template>

<script>
export default {
  data() {
    return {
      message: 'Hello'
    };
  },
  methods: {
    updateMessage() {
      // Modify the data property, but Vue.js won't detect the change automatically
      this.message += ' World';

      // Force a re-render of the component to reflect the updated message
      this.$forceUpdate();
    }
  }
};
</script>

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In this example, the initial message is 'Hello'. When the button is clicked, the updateMessage method modifies the message data property by appending ' World' to it. Since Vue.js wouldn't detect this change automatically (as it didn't use a reactive method like Vue.set or this.$set), we manually trigger a re-render of the component using this.$forceUpdate(). This forces Vue.js to update the component's DOM and display the modified message.

It's worth noting that using forceUpdate() should be done sparingly and only when necessary. Vue.js's reactivity system is designed to automatically detect and update the DOM based on changes to reactive data, and manually calling forceUpdate() can bypass this optimization. In most cases, it's recommended to let Vue.js handle reactivity and avoid the need for manual updates.

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