Can someone provide a clarification on the meaning of this Javascript code snippet?

Question

Can someone provide a clarification on the meaning of this Javascript code snippet?

I stumbled upon the code snippet below:

let customHandler;

clearTimeout(customHandler);
customHandler = setTimeout(() => {...});

This code example is actually part of a Vue application and consists of the following method:

public handleMultiSelectInput(value): void {
            if (value === "") {
              return;
            }

            clearTimeout(this.inputTimeoutHandler);
            this.inputTimeoutHandler = setTimeout(() => {
                axios.get(`${this.endpoint}?filter[${this.filterName}]=${value}`)
                  .then(response => {
                      console.log(response);
                  })
            }, 400);
        }

It seems like this is some sort of debounce function, but can someone provide more clarity on its purpose?

javascript vue.js

Answer 1

Answer №1

A debounce function is utilized to delay the execution of a certain operation until some time has passed since the last event.

In web applications, there are numerous situations where debouncing an event would be beneficial.

For instance, the code snippet you shared seems to be focusing on debouncing a text input field. Instead of immediately triggering a network request when a user starts typing in the input, it waits for 400 milliseconds after the user stops typing before making the call.

While the posted code may seem complex, the core concept behind it is clear - delaying the execution of the network request.

If I were to refactor the code, I would extract the network request like this:

const fetchData = async searchTerm => {
    const response = await axios.get(`${this.endpoint}?filter[${this.filterName}]=${value}`);
    console.log(response.data);
}

let timeoutHandler;
const onInput = event => {
    if (timeoutHandler) {
        clearTimeout(timeoutHandler);
    }
    timeoutHandler = setTimeout(() => {
        fetchData(event.target.value);
    }, 400);
}

Keep in mind that my example uses vanilla JavaScript whereas your original code resides in a Vue.js application, and without knowing the specifics of the API being accessed, some parts of the logic could be abstracted for clarity.

Answer 2

A debounce function is utilized to delay the execution of a certain operation until some time has passed since the last event.

In web applications, there are numerous situations where debouncing an event would be beneficial.

For instance, the code snippet you shared seems to be focusing on debouncing a text input field. Instead of immediately triggering a network request when a user starts typing in the input, it waits for 400 milliseconds after the user stops typing before making the call.

While the posted code may seem complex, the core concept behind it is clear - delaying the execution of the network request.

If I were to refactor the code, I would extract the network request like this:

const fetchData = async searchTerm => {
    const response = await axios.get(`${this.endpoint}?filter[${this.filterName}]=${value}`);
    console.log(response.data);
}

let timeoutHandler;
const onInput = event => {
    if (timeoutHandler) {
        clearTimeout(timeoutHandler);
    }
    timeoutHandler = setTimeout(() => {
        fetchData(event.target.value);
    }, 400);
}

Keep in mind that my example uses vanilla JavaScript whereas your original code resides in a Vue.js application, and without knowing the specifics of the API being accessed, some parts of the logic could be abstracted for clarity.

Can someone provide a clarification on the meaning of this Javascript code snippet?

Answer №1

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