Convert URL parameters to object

Read a query string into an object; repeated keys become arrays.

JavaScript Version 1.0.0 · MIT · .md

function getUrlParams(query) { return Array.from(new URLSearchParams(query)).reduce((params, [key, value]) => Object.assign(params, { [key]: Object.hasOwn(params, key) ? [].concat(params[key], value) : value }), {}); }

Input & expected output

"?utm_source=1loc.dev&tag=email&tag=webhooks"

{
  "utm_source": "1loc.dev",
  "tag": [
    "email",
    "webhooks"
  ]
}

The edge case

""

{}

Know the limits

• Values are strings; + decodes to a space as in HTML forms.
• The original checked p[k] for truthiness, so an empty first value was overwritten; Object.hasOwn keeps it.

The function above is the implementation used by the lab. The lab validates JSON types and caps size before execution; include equivalent validation when accepting untrusted input in your application.

Keep exploring

• Convert Celsius to Fahrenheit — Apply the temperature conversion without rounding the result.
• Convert hex to RGB — Expand #rgb if needed and read the red, green and blue channels.
• Convert 3 digits color to 6 digits color — Double each digit of a #rgb color.