I have a list of 2000 input checkboxes. When selecting them all at once there is noticeable delay (and browser freeze) of about 2 seconds. This seems to be the case for Vue and React, but not for Svelte or jQuery or vanilla.
With 5k+ checkboxes it becomes a very annoying 3-5 seconds blocker...
Why is the re-rendering taking so long?
How can I overcome this update delay with Vue.js?
(The solutions of paginate or lazy-load are not really solving the problem; they are avoiding it.)
Below is the code in Vue followed by the same example in Svelte.
<script setup>
import { ref } from 'vue'
const items = ref(Array.from({length: 2000}, (v, k) => k));
let selected = ref([]);
function selectAll() {
selected.value = items.value.map(i => i);
}
</script>
<template>
<button @click="selectAll">
Select all
</button>
<button @click="selected = []">
Select none
</button>
<label v-for="n in items">
<input v-model="selected" type="checkbox" :value="n">
{{ n }}
</label>
</template>
<style>
label {
display: block;
}
</style>
Svelte:
<script>
let items = Array.from({length: 2000}, (v, k) => k);
let selected = [];
function selectAll() {
selected = items.map(i => i);
}
</script>
<button on:click={selectAll}>
Select all
</button>
<button on:click="{() => selected = []}">
Select none
</button>
{#each items as n, i}
<label>
<input type=checkbox bind:group={selected} value={n}>
{n}
</label>
{/each}
<style>
label {
display: block;
}
</style>
1. The reason of slowly changes
<label v-for="n in items">
<input v-model="selected" type="checkbox" :value="n">
{{ n }}
</label>
You use v-model selected, but selected is array and you put a whole array of 2000 values in the v-model of each of the 2000 inputs, which is a lot and that's why the browser is waiting
2. Solving
You can use in input
<label v-for="n in items">
<input v-model="selected[n]" type="checkbox" :value="n">
{{ n }}
</label>
and you can change selectAll function in script
function selectAll() {
selected = items.map(i => true);
}