URLSearchParams with multiple values

I have multiples URLSearchParams created from object mainly because it’s lighter to write and to read but for some of them, I need multiple values for a "variable" like this : foo=bar&foo=baz.
For now I do it with .append but it’s heavy to read having multiple lines pretty identical.
Is there a way to do it from the constructor, with an object ?

let params;

// Currently used (and working) code
params = new URLSearchParams()
params.append("foo", "bar");
params.append("foo", "baz");

console.log(params.toString()); //Wanted result but heavy to read with more values

// Wanted code (but not the wanted result for now)

params = new URLSearchParams({
    "foo": ["bar", "baz"]
});

console.log(params.toString());

params = new URLSearchParams({
    "foo": "bar",
    "foo": "baz"
});

console.log(params.toString());

>Solution :

The URLSearchParams can takes an init value as argument for its constructor containing the following:

One of:

• A string, which will be parsed from application/x-www-form-urlencoded format. A leading '?' character
  is ignored.

• A literal sequence of name-value string pairs, or any object — such as a FormData object — with an iterator that produces a sequence of
  string pairs. Note that File entries will be serialized as [object File] rather than as their filename (as they would in an
  application/x-www-form-urlencoded form).

• A record of string keys and string values.

In your case the second one seems to work the best and can be done like this:

const searchParams = new URLSearchParams([['foo', 'bar'],['foo', 'baz'],['foo', 'qux']])

console.log(searchParams.toString())

If you want to deal with objects, you can create your own structure and use a function to create the wanted data

For example :

const params = [
  {name: "foo", values: ["bar", "baz", "qux"]},
  {name: "bar", values: ["foo", "foo2", "foo3"]},
]

const initParams = (params) => params.reduce((acc, curr) => {
  const arr = curr.values.map(x => [curr.name, x])
  return acc.concat(arr)
}, [])

const searchParams = new URLSearchParams(initParams(params))

console.log(searchParams.toString())