Vue.js: Conditional class style binding

Question

I have some data that is accessible via:

{{ content['term_goes_here'] }}

... and this evaluated to either true or false. I'd like to add a class depending on the truthiness of the expression like so:

<i class="fa" v-bind:class="[{{content['cravings']}} ? 'fa-checkbox-marked' : 'fa-checkbox-blank-outline']"></i>

where true gives me the class fa-checkbox-marked and false would give me fa-checkbox-blank-outline. The way I wrote it above gives me an error:

- invalid expression: v-bind:class="[{{content['cravings']}} ? 'fa-checkbox-marked' : 'fa-checkbox-blank-outline']"

How should I write it to be able to conditionally determine the class?

score 176 · Accepted Answer · edited Jul 15 '22 at 19:38

176

Use the object syntax.

v-bind:class="{'fa-checkbox-marked': content['cravings'],  'fa-checkbox-blank-outline': !content['cravings']}"

When the object gets more complicated, extract it into a method.

v-bind:class="getClass()"

methods:{
    getClass(){
        return {
            'fa-checkbox-marked': this.content['cravings'],  
            'fa-checkbox-blank-outline': !this.content['cravings']}
    }
}

Finally, you could make this work for any content property like this.

v-bind:class="getClass('cravings')"

methods:{
  getClass(property){
    return {
      'fa-checkbox-marked': this.content[property],
      'fa-checkbox-blank-outline': !this.content[property]
    }
  }
}

edited Jul 15 '22 at 19:38

tony19

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answered Apr 04 '17 at 14:47

Bert

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5

I refactored to: `` – Jeremy Thomas Apr 04 '17 at 14:52
1

@JeremyThomas I would go with either the array syntax or the object syntax, but not both probably. – Bert Apr 04 '17 at 14:54
yeah, i was a little surprised to see that mixed syntax in their docs. not a fan. – dave Nov 16 '17 at 21:34
How can you trigger the class binding to update when the watched properties are coming from an external source, like a `vue-router` change? (ex: `this.$router.push('/homepage')` called elsewhere in another component) – chamberlainpi Apr 12 '18 at 23:21
@bigp I expect you could watch `$route` for changes and change your classes as needed. https://router.vuejs.org/en/api/route-object.html – Bert Apr 13 '18 at 00:40

score 51 · Answer 2 · answered Apr 04 '17 at 14:48

51

<i class="fa" v-bind:class="cravings"></i>

and add in computed :

computed: {
    cravings: function() {
        return this.content['cravings'] ? 'fa-checkbox-marked' : 'fa-checkbox-blank-outline';
    }
}

answered Apr 04 '17 at 14:48

Happyriri

4,295
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3

I would have to have too many methods as there are about 20 different terms – Jeremy Thomas Apr 04 '17 at 14:53
5

Vote up for computed, its much cleaner than having expressions inside the html tags. – Johncl Nov 13 '18 at 07:36

score 45 · Answer 3 · edited Jul 15 '22 at 19:48

45

Why not pass an object to v-bind:class to dynamically toggle the class:

<div v-bind:class="{ disabled: order.cancelled_at }"></div>

This is what is recommended by the Vue docs.

edited Jul 15 '22 at 19:48

tony19

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answered Jul 09 '18 at 00:13

kaleazy

5,922
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Julio Cesar Montenegro · Answer 4 · 2018-01-04T23:56:32.760

12

the problem is blade, try this

<i class="fa" v-bind:class="['{{content['cravings']}}' ? 'fa-checkbox-marked' : 'fa-checkbox-blank-outline']"></i>

edited Jan 04 '18 at 23:56

answered Jan 04 '18 at 23:53

Julio Cesar Montenegro

210
4
8

Boussadjra Brahim · Answer 5 · 2023-07-13T16:25:43.817

10

You could use string template like below with backticks `` :

:class="`${content['cravings'] ? 'fa-checkbox-marked' : 'fa-checkbox-blank-outline'}`"

edited Jul 13 '23 at 16:25

answered Mar 27 '21 at 12:04

Boussadjra Brahim

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score 7 · Answer 6 · answered May 14 '20 at 17:09

if you want to apply separate css classes for same element with conditions in Vue.js you can use the below given method.it worked in my scenario.

html

 <div class="Main" v-bind:class="{ Sub: page}"  >

in here, Main and Sub are two different class names for same div element. v-bind:class directive is used to bind the sub class in here. page is the property we use to update the classes when it's value changed.

js

data:{
page : true;
}

here we can apply a condition if we needed. so, if the page property becomes true element will go with Main and Sub claases css styles. but if false only Main class css styles will be applied.

score 0 · Answer 7 · answered Apr 08 '23 at 17:02

There are actually multiple ways to do that. You can use the condition directly inside the v-bind like this:

<i v-bind:class="`${content['cravings'] ? 'fa-checkbox-marked' : 'fa-checkbox-blank-outline'}`">

And the other one is where you use the condition inside the script part, like this in the template:

<i v-bind:class="yourClass">

And then this in the script:

data() { 
    return { 
      yourClass = content['cravings'] ? 'fa-checkbox-marked' : 'fa-checkbox-blank-outline' 
    }
}

Vue.js: Conditional class style binding

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