/**

* 1st case

* input: '?foo=hello&bar=world'

output: {

foo: 'hello',

bar: 'world'

}

* 2nd case

* input: '?' (if there is no query after ?)

output: should be an empty object like this 👉🏻 {}

* 3rd case

* input: '?foo=hello&bar=world&baz' (if there is no equal sign)

output: {

foo: 'hello',

bar: 'world',

baz: 'true' // send by default true as string

}

* 4th case

* input: '?foo=hello&bar=world&baz&foo=again' (if there is value with the same key, have to save values as array item)

output: {

foo: ['hello', 'again], // save value as array item whick belong to save key

bar: 'world',

baz: 'true'

}

*/

const formatQueryString = (str) => {

// strip off ? and then split by &

const query = str.slice(1).split("&");

const resObj = {};

// iterate through key value pairs, split on = , and save in res object as key value

for (const pair of query) {

let [key, value= 'true'] = pair.split("="); // checking value is truthy or undefined else befault 'true' value (3rd case)

// check if key truthy else send empty object (2nd case)

if (key) {

// if there is value with the same key, have to save values as array item (4th case)

resObj[key] = resObj[key]

? typeof resObj[key] === "string"

? [resObj[key], value]

: [...resObj[key], value]

: value;

// resObj[key] = resObj[key]

// ? Array.isArray(resObj[key])

// ? [...resObj[key], value]

// : [resObj[key], value]

// : value;

}

}

return resObj;

};

console.log("1st case: ", formatQueryString("?foo=hello&bar=world"), {

foo: 'hello',

bar: 'world'

});

// console.log("2nd case: ", formatQueryString("?"), {}); // if there is no query after ?

// console.log("3rd case: ", formatQueryString("?foo=hello&bar=world&baz"), {

// foo: "hello",

// bar: "world",

// baz: "true",

// });

console.log(

"4th case: ",

formatQueryString("?foo=hello&bar=world&baz&foo=again&foo=ok&bar=again&baz&dummy&data=earth"),

{

foo: [ 'hello', 'again', 'ok' ],

bar: [ 'world', 'again' ],

baz: [ 'true', 'true' ],

dummy: 'true',

data: 'earth'

}

);

// test case

// console.log("4th case: ", formatQueryString("?foo=hello&foo"), {

// foo: ["hello", "true"],

// });