How to Make Query Strings From an Object in JavaScript

In JavaScript, you can generate query strings from an object's key-value pairs using a one-liner:

// Build query strings from object key-value pairs with
// the following line of code:

const params = {
  priceMin: 0,
  priceMax: 100,
  sort: 'asc'
};

Object.keys(params).map(key => `${key}=${params[key]}`).join('&');

// Results in the following output:
"priceMin=0&priceMax=100&sort=asc"

You only need to use Object.keys combined with a map and join. If you also need is a function, just copy the code below:

const querify = object => Object.keys(object).map(key => `${key}=${object[key]}`).join('&');

querify({
  name: 'Patrick',
  image: '⭐'
});

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How Does it Work?

To fully understand how it is working, let's go step by step and pick the function into pieces:

• First, we pass the object to Object.keys. This will return an array with each key name.
• Next, we pass it to a map function, that transforms each of the array's element into a string, namely the key of the object equal to its value.
  (${key}=${object[key]}) ➡️ "name=Patrick"
• Using join, these key-value pairs are joined together using the & sign.

You can get things done even faster by using the URLSearchParams object:

new URLSearchParams({  priceMin: 0,  priceMax: 100,  sort: 'asc'}).toString();

You just need to convert it to a string afterwards.

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Using jQuery

If you are still using jQuery, you can also achieve the same thing by using jQuery.param:

jQuery.param({  name: 'Patrick',  image: '⭐'});

• Object.keys
• Array.prototype.map
• Array.prototype.join
• URLSearchParams
• jQuery.param