How to Check if a Function is Debounced in Vue 3

Debouncing is a common technique in web development used to delay function execution until a certain period has passed without additional calls. This is useful for optimizing input handling, search queries, and event listeners. But how can we determine if a function is debounced in Vue 3?

Detecting Debounced Functions in Vue 3

In Vue 3, we often use lodash.debounce or Vue’s watchEffect and ref to debounce functions. Here’s how you can check whether a function is debounced.

1. Use a Loading State to Track Debouncing

A simple approach is to use a ref as a loading indicator, setting it to true when the function is called and resetting it after the debounce delay.

Example

<script setup>
import { ref } from "vue";
import { debounce } from "lodash";

const isDebouncing = ref(false);
const inputValue = ref("");

const debouncedFunction = debounce((value) => {
  isDebouncing.value = false;
  console.log("Debounced function executed:", value);
}, 500);

const handleInput = (event) => {
  isDebouncing.value = true;
  debouncedFunction(event.target.value);
};
</script>

<template>
  <input type="text" @input="handleInput" placeholder="Type something..." />
  <p v-if="isDebouncing">Debouncing in progress...</p>
</template>

How it Works

• The isDebouncing state is set to true when the function is called.
• It remains true while waiting for the debounce delay (500ms).
• Once the function executes, isDebouncing is set back to false, meaning no debounce is active.

2. Using Console Logs to Verify Debouncing

To confirm that a function is debounced, you can log the function calls:

const debouncedFunction = debounce((value) => {
  console.log("Function executed with:", value);
}, 500);

const handleInput = (event) => {
  console.log("Input changed:", event.target.value);
  debouncedFunction(event.target.value);
};

If the logs show only one execution after multiple rapid inputs, your function is debounced correctly.

3. Disabling Fields While Debouncing

To prevent unwanted interactions while waiting for the debounce:

<template>
  <input type="text" @input="handleInput" :disabled="isDebouncing" />
  <button :disabled="isDebouncing">Submit</button>
</template>

This prevents the user from submitting data while the function is still debouncing.

Conclusion

To check if a function is debounced in Vue 3:

• Use a ref to track debounce activity.
• Check the console logs for delayed execution.
• Disable input fields while debouncing is active.