In Vue JS, call a filter from a method inside the vue instance

Say I have a Vue instance like so:

new Vue({
    el: '#app',

    data: {
        word: 'foo',
    },

    filters: {
       capitalize: function(text) {
           return text.replace(/(?:^|\s)\S/g, function(a) { return a.toUpperCase(); });
       }
    },

    methods: {
        sendData: function() {
            var payload = this.$filters.capitalize(this.word); // how?
        }
    }
}

I can easily use the filter in a template like so:

<span>The word is {{ word | capitalize }}</span>

But how can I use this filter from within an instance method or computed property? (Obviously this example is trivial and my actual filters are more complex).

this.$options.filters.capitalize(this.word);

See http://vuejs.org/api/#vm-options

This is what worked for me

1. Defining filter

    //credit to @Bill Criswell for this filter
    Vue.filter('truncate', function (text, stop, clamp) {
        return text.slice(0, stop) + (stop < text.length ? clamp || '...' : '')
    });
   

2. Using filter

    import Vue from 'vue'
    let text = Vue.filter('truncate')(sometextToTruncate, 18);
   

if your filter is something like this

<span>{{ count }} {{ 'item' | plural(count, 'items') }}</span>  

this is the answer

this.$options.filters.plural('item', count, 'items')

You can create a vuex like helper function to map globally registered filters into the methods object of a vue component:

// map-filters.js
export function mapFilters(filters) {
    return filters.reduce((result, filter) => {
        result[filter] = function(...args) {
            return this.$options.filters[filter](...args);
        };
        return result;
    }, {});
}

Usage:

import { mapFilters } from './map-filters';

export default {
    methods: {
        ...mapFilters(['linebreak'])
    }
}

To complement Morris answer, this is an example of a file I normally use to put filters inside, you can use in any view using this method.

var Vue = window.Vue
var moment = window.moment

Vue.filter('fecha', value => {
  return moment.utc(value).local().format('DD MMM YY h:mm A')
})

Vue.filter('ago', value => {
  return moment.utc(value).local().fromNow()
})

Vue.filter('number', value => {
  const val = (value / 1).toFixed(2).replace('.', ',')
  return val.toString().replace(/\B(?=(\d{3})+(?!\d))/g, '.')
})
Vue.filter('size', value => {
  const val = (value / 1).toFixed(0).replace('.', ',')
  return val.toString().replace(/\B(?=(\d{3})+(?!\d))/g, '.')
})

Try:

this.$options.filters.capitalize