/** Object.entries method (ES2017)*/
let obj = {one: 1, two: 2, three: 3};
//convert from object to array (key-value)
console.log(Object.entries(obj)); // =>[["one", 1], ["two", 2], ["three", 3]]

/** Object.fromEntries method (ES2019) */

//This is reverse method
//first example
const myArr = [['one', 1], ['two', 2], ['three', 3]];
obj = Object.fromEntries(myArray);
console.log(obj); // => {one: 1, two: 2, three: 3}

//second example
const map = new Map();
map.set('one', 1);
map.set('two', 2);
obj = Object.fromEntries(map);
console.log(obj); // => {one: 1, two: 2}

//example with url's params
const paramsString = 'param1=foo&param2=baz';
const searchParams = new URLSearchParams(paramsString);
Object.fromEntries(searchParams); // => {param1: "foo", param2: "baz"}



/** trimStart() and trimEnd() methods (ES2019) */
const str = "   string   ";
console.log(str.trimStart());    // => "string   "
console.log(str.trimEnd());      // => "   string"

/** trimLeft() and trimRight() methods */
console.log(str.trimLeft());     // => "string   "
console.log(str.trimRight());    // => "   string"



/** flat() and flatMap() methods (ES2019) */
/** flat() */
let arr = ['a', 'b', ['c', 'd']];
let flattened = arr.flat();
console.log(flattened);    // => ["a", "b", "c", "d"]

arr = ['a', , , 'b', ['c', 'd']];
flattened = arr.flat();
console.log(flattened);    // => ["a", "b", "c", "d"]

/** flat() also accepts an optional argument that specifies the number of levels a nested array should be flattened.
If no argument is provided, the default value of 1 will be used: */
arr = [10, [20, [30]]];
console.log(arr.flat());     // => [10, 20, [30]]
console.log(arr.flat(1));    // => [10, 20, [30]]
console.log(arr.flat(2));    // => [10, 20, 30]

/** flatMap() */
const arr = [4.25, 19.99, 25.5];
console.log(arr.map(value => [Math.round(value)])); // => [[4], [20], [26]]
console.log(arr.flatMap(value => [Math.round(value)])); // => [4, 20, 26]

/** String.proptotype.matchAll (ES2020) */
const re = /(Dr\. )\w+/g;
const str = 'Dr. Smith and Dr. Anderson';
const matches = str.matchAll(re);
for (const match of matches) {
  console.log(match);
}

// logs:
// => ["Dr. Smith", "Dr. ", index: 0, input: "Dr. Smith and Dr. Anderson", groups: undefined]
// => ["Dr. Anderson", "Dr. ", index: 14, input: "Dr. Smith and Dr. Anderson", groups: undefined]