I am quite new to Vue and I have an issue.
I have an array of objects and I want the wrapper of the loop to have dynamic className
For example
<div v-for="({time, date, name}, i) in myObject" :key="i" class="my-custom-class">
well, if the key (i) is greater than 3 then I want the className to have a different name
or at least to add an extra name (like hiddenDiv).
I know is not possible to add the v-if condition in the v-for statement.
Any help is appreciated.
You could bind the class using a condition based on the current loop index :class="{'hide-div':i>3}":
<div v-for="({time, date, name}, i) in myObject"
:key="i" :class="{'hide-div':i>3}" class="my-custom-class" >
Another way of doing this using computed property...
<div v-for="({time, date, name}, i) in myObject"
:key="i" :class="getClassName(i)" class="my-custom-class" >
and in your computed
computed: {
getClassName() {
return i => {
if(i === 0) return 'classOne';
elseif(i === 1) return 'classTwo'
else return 'classThree';
// In this way you can maintain as many classNames you want based on the condition
}
}
}
If you want to apply a dynamic class in vue then you can use class bindings to apply a specific class to the element.
You can read about class and style bindings here.
Also, you can define a method with the class and apply some conditions on which the class needs to be changed.
Related
Here's my code:
<div v-for="(message) in messages">
<div class="message-divider sticky-top pb-2" data-label="Test"> </div>
...
What I need to achieve is, if current iteration's message.createdAt.seconds differs by day from the previous one to show message-divider element.
So the time format is in seconds like this: 1621515321
How can I achieve this?
You can do variable assignment as part of the template, so you could assign the previous value and compare, but this is not a very good idea. Instead you can use a computed to prepare your array to only have the objects you want, with the data you need. So in this case, you could use a computed to create a new array with objects that have additional flags like className or showDivider etc.
example:
computed:{
messagesClean(){
let lastCreatedAt;
return this.messages.map(message => {
const ret = {
...message,
showDivider: lastCreatedAt + 3600*24 < message.createdAt.seconds // your custom logic here
}
lastCreatedAt = message.createdAt.seconds
return ret
}
}
}
the logic to determine when the divider gets shown is up to you there, I suspect it may be a bit more complicated than differing by a day.
You need something like this:
<div v-if="compEqRef">
OK
</div>
<div v-else >!!OK!!</div>
Here compEqRef could be in computed:
computed: {
compEqRef() {
//do something
}
},
I have this template displaying a list of components:
<template>
<v-container id="container">
<RaceItem v-for="(item, index) in items" :key="item + index" />
(...)
When the array "items" is updated (shift() or push() a new item), the list displayed is not updated.
I'm sure I'm missing something on how Vue works... but could anyone explain what's wrong?
The key attribute expects number | string | boolean | symbol. It is recommended to use primitives as keys.
The simplest usage is to use a primitive unique property of each element to track them:
<RaceItem v-for="item in items" :key="item.id" />
... assuming your items have unique ids.
If you use the index as key, every time you update the array you'll have to replace it with an updated version of itself (i.e: this.items = [...items]; - where items contains the mutation).
Here's how your methods would have to look in that case:
methods: {
applyChangeToItem(item, change) {
// apply change to item and return the modified item
},
updateItem(index, change) {
this.$set(
this.items,
index,
this.applyChangeToItem(this.items[index], change)
);
},
addItem(item) {
this.items = [...this.items, item];
},
removeItem(index) {
this.items = [...this.items.filter((_, i) => index !== i)];
}
}
Can you try something like this
Put componentKey on v-container and use forceRender() after your push is done
I'd like to do v-for loop for creating a div. I'm doing a minesweeper game and here is my code :
<div class="grid">
<div class="square"
v-for="(square, index) in squares"
:id="index"
:key="index"
:class="squares[index]"
#click="clicked(square, index)"
>
</div>
</div>
'Squares' in this code is an array with shuffled classes 'bomb' or 'empty'. I know that it's wrong because after I click on random square I get only this class from te 'squares' array. What should be there instead of this 'squares' array in v-for. I want to get whole with classes, attributes etc. because later I have to use 'classList' 'contains' etc.
Sorry, maybe I'm completly wrong and talking bullshit, but I started with vue 3 weeks ago.
Here is the method clicked which I want to use
clicked(square) {
if(this.isGameOver) return;
if(square.classList.contains('chechked') || square.classList.contains('flag')) return
if(square.classList.contains('bomb')) {
this.gameOver(square);
} else {
let total = square.getAttribute('data');
if(total != 0) {
square.classList.add('checked');
square.innerHTML = total;
return
}
}
square.classList.add('checked');
}
You want to access the div element but you are passing the object in the method and you are asking for classList into the object (that does not have it). You should query the element instead.
Change the #click handler in your component to:
#click="clicked"
and your method to:
clicked(event) {
let square = event.target;
console.log(square);
console.log(square.classList);
...
Good evening,
My problem is this: I have a loop that displays simple divs.
I have a method that specifies the dimensiosn of my div (mandatory in my case). However, when I call the method a second time by changing the sizes of the divs, it does not work because there is no re-render.
To overcome this, I generate a guid on my: key of v-for with a variable such as:
<div v-for="task in tasks" :key="task.id + guid()">...blabla...</div>
Is it possible to generate this code directly during the loop to avoid concatenation?
<div v-for="(task, maVar=guid()) in tasks" :key="maVar">...blabla...</div>
PS : code for guid() method :
guid() {
return ([1e7] + -1e3 + -4e3 + -8e3 + -1e11).replace(/[018]/g, c =>
(c ^ crypto.getRandomValues(new Uint8Array(1))[0] & 15 >> c / 4).toString(16))
}
Thanks
You could create a computed property that returns an array of task with a guid added, or if you want to leave tasks untouched, return an object containing each task plus a guid,
computed: {
tasksWithGuid: function() {
return this.tasks.map(task => { return {task, key: task.id + guid() } })
}
}
<div v-for="taskWithGuid in tasksWithGuid" :key="taskWithGuid.key">
{{taskWithGuid.task.someProperty}}
</div>
There is a simpler, more concise technique shown below. It avoids polluting the iterated object with a redundant property. It can be used when there is no unique property in the objects you iterate over.
First in your viewmodel add the method to generate a random number (e.g. with Lodash random)
var random = require('lodash.random');
methods: {
random() {
return random(1000);
}
}
Then in your template reveal the index in v-for and randomize it in v-bind:key with your random() method from the viewmodel by concatenation.
<div v-for="(task, index) in tasks" v-bind:key="index + random()">
// Some markup
</div>
This is as clean as easy.
However note this approach would force redrawing each item in the list instead of replacing only items that differ. This will reset previously drawn state (if any) for unchanged items.
I do like this
function randomKey() {
return (new Date()).getTime() + Math.floor(Math.random() * 10000).toString()
}
I have this html element:
Link text
I want to add data-tooltip and title attributes dynamically by condition:
Link text
Is there any way in VueJS to add multiple dynamic attributes at same time:
<!-- instead of this: -->
Link text
<!-- something like this: -->
<a href="javascript:" ...tooltipAttributes >Link text</a>
You could take advantage of v-bind on the DOM element you wish to apply multiple attributes to based on some dynamically changing condition.
Here's a Plunker example demonstrating how you might go about it.
Take note of the object returned:
computed: {
multiAttrs() {
return this.showAttrs ? {
'data-toggle': 'tooltip',
title: 'Some tooltip text',
} : null;
}
}
You should be able to use v-bind="tooltipAttributes"
the docs here https://v2.vuejs.org/v2/api/#v-bind have more info, but the key part is under usage
Dynamically bind one or more attributes, or a component prop to an expression.
From the Docs:
1. You can dynamically bind multiple attributes/props to a single element by using v-bind:
(no colon, no extra attribute, just v-bind)
<a href="#" v-bind="tooltipAttributes" >Link text</a>
2. And then declare the variable in the computed section:
(you can also declare it in the data section, but that would require manual direct value changes)
computed() {
return {
tooltipAttributes: {
title: 'Title',
'data-toggle': this.toggle === true && !disabled
}
}
}
Note: Attributes with dashes/hyphens - in them (e.g. data-toggle) need to be a string because Javascript doesn't recognize - as a valid symbol in variable naming.
This is THE SAME AS:
<a href="#" title="Title" :data-toggle="this.toggle === true && !disabled" >Link text</a>