Mastering Vue.js: Unlocking the Power of $nextTick

Unlocking the Power of Vue’s $nextTick

Imagine walking into a Vue bar, ordering your favorite Nuxt cocktail, and striking up a conversation with the bartender about the mysteries of $nextTick. As a seasoned frontend developer, you’ve worked with Vue for a while, but you’re still puzzled by this instance method. What exactly does it do, and why is it essential for your Vue projects?

Understanding the Basics

Before we dive deeper, make sure you have a solid grasp of the following concepts:

• Event loops
• Callback functions
• Microtasks, queues, and schedules
• Async update queues

What is $nextTick?

$nextTick is a Vue method that accepts a callback function, delaying its execution until the next DOM update cycle. Think of it as Vue’s way of saying, “Hey, if you want to execute a function after the DOM has been updated, use $nextTick instead of setTimeout.”

Visualizing $nextTick Behavior

Let’s explore an example to illustrate how $nextTick works:

js
export default {
data() {
return {
count: 0
}
},
mounted() {
this.count = 3
this.$nextTick(() => {
this.count = 2021
})
}
}


Run this code snippet, and you’ll see the count update to 2021. But why? Vue updates the DOM to 3, then invokes the callback, updates the DOM to 2021, and finally gives control to the browser, which displays 2021.

$nextTick vs. setTimeout

So, what’s the difference between $nextTick and setTimeout? Let’s replace $nextTick with setTimeout in our previous example:

js
export default {
data() {
return {
count: 0
}
},
mounted() {
this.count = 3
setTimeout(() => {
this.count = 2021
}, 0)
}
}


Run this code, and you’ll see the count update to 3 first, followed by 2021. This is because Vue updates the DOM to 3, gives the browser control, displays 3, invokes the callback, updates the DOM to 2021, and finally gives control to the browser again.

When to Use $nextTick

There are specific scenarios where $nextTick shines:

• When you want to ensure the DOM reflects your data accurately
• When you encounter errors like Uncaught (in promise) DOMException while performing asynchronous actions
• When you need to use setTimeout, but with a Vue twist

Real-World Example: Smooth Scrolling

Let’s explore a practical use case for $nextTick in Vue 3:

js
export default {
data() {
return {
items: []
}
},
methods: {
addItem() {
this.items.push({ id: 1, name: 'New Item' })
this.$nextTick(() => {
const element = document.getElementById('scroll-to-me')
element.scrollIntoView({ behavior: 'mooth' })
})
}
}
}


Run this code, and you’ll see a smooth scroll-down effect when a new item is added to the list. Remove $nextTick, and the effect disappears.

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