Retrieve vue instance/data from within a filter method

Question

Retrieve vue instance/data from within a filter method

I'm attempting to access the data of a Vue instance within a filter function as shown below. JS:-

new Vue({
 data:{
  amount: 10,
  exchangeRate:50
 },
 el:"#app",
 filters:{
   currency: function(amount){
             console.log(this);
             //return amount * this.exchangeRate;
            return amount *50;

   }
 }
})

HTML:

<div id="app">
 {{ amount | currency}}
</div>

My objective is to use

return amount * this.exchangeRate;

, however, in this context, this refers to window. How can I achieve this? Thanks. jsfiddle

javascript vue.js vuejs2

Answer 1

Answer №1

Evan, the founder of Vue, suggests different use cases for methods, filters, and computed properties:

Methods should be used primarily for changing state. When you invoke a method, it usually results in some side effect.

Filters are best utilized for basic text formatting that needs to be reused throughout your application. They should be pure functions - no side effects, just input and output data.

Computed properties are ideal for handling local data transformations within components. Like filters, computed getters should also be pure functions.

In certain scenarios where you need to calculate something with a template-only variable (like a v-for alias), it's acceptable to use "helper methods" to compute values by passing arguments.

(source: )

Considering that the filter relies on the component, it may be more appropriate to use a computed property instead of a filter in this particular case.

Answer 2

Evan, the founder of Vue, suggests different use cases for methods, filters, and computed properties:

Methods should be used primarily for changing state. When you invoke a method, it usually results in some side effect.

Filters are best utilized for basic text formatting that needs to be reused throughout your application. They should be pure functions - no side effects, just input and output data.

Computed properties are ideal for handling local data transformations within components. Like filters, computed getters should also be pure functions.

In certain scenarios where you need to calculate something with a template-only variable (like a v-for alias), it's acceptable to use "helper methods" to compute values by passing arguments.

(source: )

Considering that the filter relies on the component, it may be more appropriate to use a computed property instead of a filter in this particular case.

Answer 3

Answer №2

Edit made this way:

new Vue({
 data:{
  amount: 10,
  exchangeRate:60
 },
 el:"#app",
 filters:{
   currency: function(amount, exchange){
             console.log(exchange);
             //return amount * this.exchangeRate; <- can't do, must pass it in
            return amount * exchange;

   }
 }
})

<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.6.11/vue.min.js"></script>
<div id="app">
 {{ amount | currency(exchangeRate)}}
</div>

Answer 4

Edit made this way:

new Vue({
 data:{
  amount: 10,
  exchangeRate:60
 },
 el:"#app",
 filters:{
   currency: function(amount, exchange){
             console.log(exchange);
             //return amount * this.exchangeRate; <- can't do, must pass it in
            return amount * exchange;

   }
 }
})

<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.6.11/vue.min.js"></script>
<div id="app">
 {{ amount | currency(exchangeRate)}}
</div>

Answer 5

Answer №3

There are two crucial options available to you: utilizing a method/computed property or passing an additional parameter to filter. Attempting to access this within a filter is not possible, as the purpose of filters is intended for simple tasks such as text transformation, as explained in the documentation:

Filters are predominantly meant for text transformation purposes. For more intricate data transformations with other directives, it is recommended to use Computed properties instead.

Answer 6

There are two crucial options available to you: utilizing a method/computed property or passing an additional parameter to filter. Attempting to access this within a filter is not possible, as the purpose of filters is intended for simple tasks such as text transformation, as explained in the documentation:

Filters are predominantly meant for text transformation purposes. For more intricate data transformations with other directives, it is recommended to use Computed properties instead.

Retrieve vue instance/data from within a filter method

Answer №1

Answer №2

Answer №3

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