What is better in vue.js 2, use v-if or v-show?

Question

I'm working in a project with vue 2. I need to know in which case the performance is better: Use v-if or v-show?. I have a long list and each item's list has a form hidden that I need show and hide to click a button that has each item list. What is better a toggle class of v-show or add and remove the form with v-if?

Solution 1

tl;dr

Assuming the question is strictly about performance:

• v-show: expensive initial load, cheap toggling,
• v-if: cheap initial load, expensive toggling.

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Evan You provided a more in depth answer at VueJS Forum

v-show always compiles and renders everything - it simply adds the "display: none" style to the element. It has a higher initial load cost, but toggling is very cheap.

Incomparison, v-if is truely conditional: it is lazy, so if its initial condition is false, it won't even do anything. This can be good for initial load time. When the condition is true, v-if will then compile and render its content. Toggling a v-if block actually tearsdown everything inside it, e.g. Components inside v-if are acually destroyed and re-created when toggled, so toggling a huge v-if block can be more expensive than v-show.

Solution 2

Short answer:

Use v-if if the condition won't change that often.

Use v-show if you want to toggle the condition more often.

Note: v-show does not remove the element from the DOM if your condition is false. So people can see it when they inspect your page.

Solution 3

Adding that usage of 'v-if' can have unexpected consequences, since it connects and disconnects elements from the DOM instead of modifying the elements' display.

For example, if you use it on a form and end up toggling that form off using v-if, you will receive this browser console warning:

    “Form submission canceled because the form is not connected”

If you use 'v-show', you won't encounter this problem.

Solution 4

v-show just only toggles display property of CSS(either "none" or "block"). When we use v-show the HTML DOM will be on the page only(with the "display" property).

But where as if we use v-if it removes the entire DOM from the page or recreates the entire DOM based on the condition.

Check this example.

<p v-if="ok">If Check</p>
<p v-show="ok">Show Check</p> //try to set "ok" by true and false and inspect HTML

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Comments

[radbyx]

The link is broken.

[Magiczne]

Your answer does not add anything new to the question, because info you have provided already exists in other answers.