bootstrapvue-navbar.js

//src/components/Navbar.vue
<template>
    <div>
      <b-navbar toggleable="lg" type="dark" variant="success">
        <b-container>
            <b-navbar-brand href="#">Mealzers</b-navbar-brand>
            <b-navbar-toggle target="nav-collapse"></b-navbar-toggle>
            <b-collapse id="nav-collapse" is-nav>
              <!-- Right aligned nav items -->
              <b-navbar-nav class="ml-auto">
                <b-nav-form>
                  <b-form-input 
                    size="sm" 
                    class="mr-sm-2" 
                    placeholder="Search for a meal"
                    v-model="meal"
                    ></b-form-input>
                  <b-button 
                    size="sm" 
                    class="my-2 my-sm-0" 
                    type="submit" 
                    @click.prevent="getMeal"
                    >Search</b-button>
                </b-nav-form>
                <b-nav-item-dropdown right>
                  <!-- Using 'button-content' slot -->
                  <template slot="button-content"><em>User</em></template>
                  <b-dropdown-item href="#">Profile</b-dropdown-item>
                  <b-dropdown-item href="#">Sign Out</b-dropdown-item>
                </b-nav-item-dropdown>
              </b-navbar-nav>
            </b-collapse>
          </b-container>
      </b-navbar>
    </div>  
</template>
<script>
export default {
    data() {
        return {
            meal: ''
        }
    },
  methods: {
    getMeal() {
      ...
    }
  }
}    
</script>

Just tried the example, but got an error in Line# 47 : Unexpected token '...'

ERROR Failed to compile with 1 errors

error in ./src/components/Navbar.vue?vue&type=script&lang=js&

Syntax Error: SyntaxError: D:\Work\bootstrapvue\bootstrapvue-demo\src\components\Navbar.vue: Unexpected token (47:6)

45 | methods: {
46 | getMeal() {

47 | ...
| ^
48 | }
49 | }
50 | }

Removing line 47 (the "..." one) will get it compiling so that you can display the page. I assume some code will need to be added there, but have yet to work out what.