Vue For Loop

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Vue js for loop (v-for) example tutorial.

In this tutorial, you will learn how to use for loop or v-for in vue js or How to loop through a list of elements and display it in VueJS.

This tutorial will guide you step by step on how to use for loop or v-for in vue js.

And as well as, you can use the v-for directive to render a list of items based on an array.

3. Avoid use v-if in loops

Note that, The v-for directive requires a special syntax in the form of item in items, where items is the source data array and item is an alias for the array element being iterated on.

And you can use use for loop or v-for loop in vue js for: .

Rendering arrays or lists. Iterating through the properties of an object. This tutorial will show you two examples of how to use for loop or v-for loop in vue js:.

The following code will print items from list of array in vue js:. The following code will print items from list of array in vue js:.

The following code will print items from list of array in vue js:. vue js for loop example tutorial you have learn how to use for loop or v-for loop in vue js.

In Vue, v-for loops are something that every project will use at some point or another.

They allow you to write for loops in your template code. This is awesome for things like…. Rendering arrays or lists. Iterating through an objects properties.

Using v-for with Arrays

In its most basic usage, Vue v-for loops are used like this. However, in this article, we’ll be covering some amazing ways to make your v-for code more precise, predictable, and efficient.

Alright – let’s dive right in.

To start off, we’ll be discussing a common best practice most Vue developers already know – use :key in your v-for loops.

By setting a unique key attribute, it ensures that your component works the way you’d expect.

If we don’t use keys, Vue will try to make the DOM as efficient as possible. This may mean that v-for elements may appear out of order or other unpredictable behavior.

If we have a unique key reference to each element, then we can better predict how exactly the DOM will be manipulated.

Filtering Lists

While most of the time v-for is used to loop over arrays or objects, there are definitely cases where we might just want to iterate a certain number of times.

For example, let’s say we are creating a pagination system for an online store and we only want to show 10 products per page.

Using a variable to track our current page number, we could handle pagination like this.

A super common mistake is to improperly use v-if to filter the data that we are looping over with our v-for.

Although this seems intuitive, it causes a huge performance issue – VueJS prioritizes the v-for over the v-if directive.

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What this means is that your component will loops through every element and THEN checks the v-if conditional to see if it should render.

So what’s the issue? Let’s say our products array has thousands of items, but there only 3 products on sale that we want to render.

Every time we re-render, Vue will have to loop over thousands of items even if the 3 products on sale did not change at all.

Try to avoid this. Let’s look at two alternatives we can use instead of joining v-for with v-if.

To avoid the above problem, we should filter our data BEFORE iterating over it in our template.

There are two very similar ways to do this:. Using a computed property. Using a filtering method. The way you choose to do this is up to you, so let’s just cover both real quick.

First, we just have to set up a computed property. To get the same functionality as our earlier v-if, the code would look like this.

This has a few benefits:. Our data property will only be re-evaluated when a dependency changes.

Using v-for with Objects

Our template will only loop over the products on sale, instead of every single product.

The code for the method is pretty much the same, but using a method changes how we access the values in our template.

However, if we want to be able to pass in a variable to filtering process, methods are the way to go.

How to use for loop or v-for in vue js

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