<p dir="auto">Params specified using axios.create are ignored. Here's a test case:</p>
<div class="highlight highlight-source-js notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="const axios = require('axios');

const agent = axios.create({
  baseURL: 'https://www.test.com',
  params: {
    test: 'test',
  },
});

Promise.all([
  agent.get('/'),
  agent.get('/', { params: { foobar: 'foo' } }),
]).then((arr) =&gt; arr.map(({ request: { path } }) =&gt; console.log(path)));"><pre class="notranslate"><span class="pl-k">const</span> <span class="pl-s1">axios</span> <span class="pl-c1">=</span> <span class="pl-en">require</span><span class="pl-kos">(</span><span class="pl-s">'axios'</span><span class="pl-kos">)</span><span class="pl-kos">;</span>

<span class="pl-k">const</span> <span class="pl-s1">agent</span> <span class="pl-c1">=</span> <span class="pl-s1">axios</span><span class="pl-kos">.</span><span class="pl-en">create</span><span class="pl-kos">(</span><span class="pl-kos">{</span>
  <span class="pl-c1">baseURL</span>: <span class="pl-s">'https://www.test.com'</span><span class="pl-kos">,</span>
  <span class="pl-c1">params</span>: <span class="pl-kos">{</span>
    <span class="pl-c1">test</span>: <span class="pl-s">'test'</span><span class="pl-kos">,</span>
  <span class="pl-kos">}</span><span class="pl-kos">,</span>
<span class="pl-kos">}</span><span class="pl-kos">)</span><span class="pl-kos">;</span>

<span class="pl-v">Promise</span><span class="pl-kos">.</span><span class="pl-en">all</span><span class="pl-kos">(</span><span class="pl-kos">[</span>
  <span class="pl-s1">agent</span><span class="pl-kos">.</span><span class="pl-en">get</span><span class="pl-kos">(</span><span class="pl-s">'/'</span><span class="pl-kos">)</span><span class="pl-kos">,</span>
  <span class="pl-s1">agent</span><span class="pl-kos">.</span><span class="pl-en">get</span><span class="pl-kos">(</span><span class="pl-s">'/'</span><span class="pl-kos">,</span> <span class="pl-kos">{</span> <span class="pl-c1">params</span>: <span class="pl-kos">{</span> <span class="pl-c1">foobar</span>: <span class="pl-s">'foo'</span> <span class="pl-kos">}</span> <span class="pl-kos">}</span><span class="pl-kos">)</span><span class="pl-kos">,</span>
<span class="pl-kos">]</span><span class="pl-kos">)</span><span class="pl-kos">.</span><span class="pl-en">then</span><span class="pl-kos">(</span><span class="pl-kos">(</span><span class="pl-s1">arr</span><span class="pl-kos">)</span> <span class="pl-c1">=&gt;</span> <span class="pl-s1">arr</span><span class="pl-kos">.</span><span class="pl-en">map</span><span class="pl-kos">(</span><span class="pl-kos">(</span><span class="pl-kos">{</span> <span class="pl-c1">request</span>: <span class="pl-kos">{</span> path <span class="pl-kos">}</span> <span class="pl-kos">}</span><span class="pl-kos">)</span> <span class="pl-c1">=&gt;</span> <span class="pl-smi">console</span><span class="pl-kos">.</span><span class="pl-en">log</span><span class="pl-kos">(</span><span class="pl-s1">path</span><span class="pl-kos">)</span><span class="pl-kos">)</span><span class="pl-kos">)</span><span class="pl-kos">;</span></pre></div>
<p dir="auto">EXPECTED OUTPUT:<br>
/?test=test<br>
/?test=test&amp;foobar=foo</p>
<p dir="auto">ACTUAL OUTPUT<br>
/<br>
/?foobar=foo</p>
<p dir="auto"><strong>Describe the bug</strong></p>
<p dir="auto">Specific request params do not get merged with the instance default params.</p>
<p dir="auto"><strong>To Reproduce</strong></p>
<div class="highlight highlight-source-js notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="const instance = axios.create({
    baseURL: &quot;http://www.example.com&quot;,
    params: {
      q: &quot;question&quot;,
    }
  });"><pre class="notranslate"><span class="pl-k">const</span> <span class="pl-s1">instance</span> <span class="pl-c1">=</span> <span class="pl-s1">axios</span><span class="pl-kos">.</span><span class="pl-en">create</span><span class="pl-kos">(</span><span class="pl-kos">{</span>
    <span class="pl-c1">baseURL</span>: <span class="pl-s">"http://www.example.com"</span><span class="pl-kos">,</span>
    <span class="pl-c1">params</span>: <span class="pl-kos">{</span>
      <span class="pl-c1">q</span>: <span class="pl-s">"question"</span><span class="pl-kos">,</span>
    <span class="pl-kos">}</span>
  <span class="pl-kos">}</span><span class="pl-kos">)</span><span class="pl-kos">;</span></pre></div>
<div class="highlight highlight-source-js notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="instance.get(&quot;/page&quot;, 
  { 
    params: { 
      page: 2 
    }
  }
)"><pre class="notranslate"><span class="pl-s1">instance</span><span class="pl-kos">.</span><span class="pl-en">get</span><span class="pl-kos">(</span><span class="pl-s">"/page"</span><span class="pl-kos">,</span> 
  <span class="pl-kos">{</span> 
    <span class="pl-c1">params</span>: <span class="pl-kos">{</span> 
      <span class="pl-c1">page</span>: <span class="pl-c1">2</span> 
    <span class="pl-kos">}</span>
  <span class="pl-kos">}</span>
<span class="pl-kos">)</span></pre></div>
<p dir="auto">What happens is that the request param object overrides the instance default param object. The instance no longer has a query param of <code class="notranslate">q</code>.</p>
<p dir="auto"><strong>Expected behavior</strong></p>
<p dir="auto">According to the docs, all configuration options are <em>merged</em>. <a href="https://github.com/axios/axios#instance-methods">https://github.com/axios/axios#instance-methods</a></p>
<p dir="auto">I expected request to contain both <code class="notranslate">q</code> and <code class="notranslate">page</code> params. This is also how it was working in version 0.18.0, which is how I noticed.</p>
<p dir="auto"><strong>Environment:</strong></p>
<ul dir="auto">
<li>Axios Version: 0.19.0</li>
<li>OS: 10.14.5 (18F132)</li>
<li>Browser: Node Express, and Chrome</li>
<li>Browser: Node 10.15.0, Chrome Version 74.0.3729.169 (Official Build) (64-bit)</li>
</ul>