<pre class="shiki github-dark shaku"><code>/** * @param {any} arg * @returns {any} */function undefinedToNull(arg) { if(typeof(arg) === "undefined" || arg === null){ return null; } if(typeof(arg) !== "object"){ return arg; } for (key in arg) { arg[key] = undefinedToNull(arg[key]); } return arg;}</code></pre>

Recursive solution

One of the differences between null and undefined is how they are treated differently in JSON.stringify(). JSON.stringify({a: null}) // '{"a":null}'JS…