How to add token when using axios to send an ajax request?
<p>I am using Laravel <code>5.3</code> and vue.js <code>2.0</code>，<br>
And I use axios (<a href="https://github.com/mzabriskie/axios" rel="nofollow noreferrer">https://github.com/mzabriskie/axios</a>) to send ajax requests,<br>
I follow the docs to set the <code>TOKEN</code> like this:</p>

<pre><code>&lt;script&gt;

    axios.defaults.headers.common['Authorization'] = AUTH_TOKEN;  //The error is at this line.

    new Vue({
        el: "#app",
        data: function () {
            return {
                items: []
            }
        },
        mounted: function () {
            this.$nextTick(function () {
                axios.get('/articles').then(function (response) {
                    response.data.forEach(function (item) {
                        item.selected = false;
                    });
                    this.items = response.data;
                }).catch(function (error) {

                    console.log(error);
                });
            });
        }
    });
&lt;/script&gt;
</code></pre>

<p>the error in console is like this:</p>

<pre><code>Uncaught ReferenceError: AUTH_TOKEN is not defined 
</code></pre>

<p>What should I do?</p>