Vue.js how to use npm plugins

Question

I have tried multiple different plugins with my Vue.js cli webpack projects and I am getting the same problem with all of them, namely that once I have included a plugin, I am unable to use it.

As an example. I have tried to use the plugin at this link. https://www.npmjs.com/package/vue-sessionstorage

Here is my main.js file

import Vue from 'vue'
import router from './router'
import VueMaterial from 'vue-material'
import { store } from './store'
import 'vue-material/dist/vue-material.css'
import 'vue-style-loader'
import VueSessionStorage from 'vue-sessionstorage'

import App from './App'

Vue.use(VueMaterial, VueSessionStorage);


Vue.config.productionTip = false;


/* eslint-disable no-new */
new Vue({
    el: '#app',
    router,
    store,
    template: '<App/>',
    components: { App },

});

I have run npm install --save vue-sessionstorage

As you can see, I have also imported VueSessionStorage

However, when I try to use it like this

methods: {
            login: function () {
                console.log("Login clicked");
                this.$session.set('username','simon')
                console.log(this.$session.get('username'));
            },
            register: function () {
                console.log(this.$session.get('username'));

            }
        }

I get the error

vue.esm.js?65d7:563 TypeError: Cannot read property 'set' of undefined
    at VueComponent.login (Login.vue?2ddf:35)
    at boundFn (vue.esm.js?65d7:179)
    at Proxy.invoker (vue.esm.js?65d7:1821)
    at Proxy.Vue.$emit (vue.esm.js?65d7:2331)
    at click (mdButton.vue?3bf8:38)
    at HTMLButtonElement.invoker (vue.esm.js?65d7:1821)
handleError @ vue.esm.js?65d7:563
Vue.$emit @ vue.esm.js?65d7:2333
click @ mdButton.vue?3bf8:38
invoker @ vue.esm.js?65d7:1821

Answer 1

Vue.use does not permit multiple plugins to be initialized at once like that. Initialize them as two separate calls:

Vue.use(VueMaterial);
Vue.use(VueSessionStorage);