Typescript error: TS7053 Element implicitly has an 'any' type : <p>this is part of my code:</p>

<pre class="lang-js prettyprint-override"><code>const myObj: object = {}
const propname = 'propname'

myObj[propname] = 'string'
</code></pre>

<p>but I got error:</p>

<pre class="lang-sh prettyprint-override"><code>ERROR in path/to/file.ts(4,1)
TS7053: Element implicitly has an 'any' type because expression of type '"propname"' can't be used to index type '{}'.
  Property 'propname' does not exist on type '{}'.
</code></pre>

<p>What is wrong here, and how can I fix it?</p>
