flatten array js code example

Example 1: javascript array flat

var arr1 = [1, 2, [3, 4]];
arr1.flat(); 
// [1, 2, 3, 4]

var arr2 = [1, 2, [3, 4, [5, 6]]];
arr2.flat();
// [1, 2, 3, 4, [5, 6]]

var arr3 = [1, 2, [3, 4, [5, 6]]];
arr3.flat(2);
// [1, 2, 3, 4, 5, 6]

Example 2: javascript array flatten

// flat(depth), 
// depth is optional: how deep a nested array structure 
//		should be flattened.
//		default value of depth is 1 

const arr1 = [1, 2, [3, 4]];
arr1.flat(); 
// [1, 2, 3, 4]

const arr2 = [1, 2, [3, 4, [5, 6]]];
arr2.flat();
// [1, 2, 3, 4, [5, 6]]

const arr3 = [1, 2, [3, 4, [5, 6]]];
arr3.flat(2);
// [1, 2, 3, 4, 5, 6]

const arr4 = [1, 2, [3, 4, [5, 6, [7, 8, [9, 10]]]]];
arr4.flat(Infinity);
// [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

Example 3: array flatten

const arr = [1, 2, [3, 4]];

// To flat single level array
arr.flat();
// is equivalent to
arr.reduce((acc, val) => acc.concat(val), []);
// [1, 2, 3, 4]

// or with decomposition syntax
const flattened = arr => [].concat(...arr);

Example 4: flatten an array javascript

var arrays = [
  ["$6"],
  ["$12"],
  ["$25"],
  ["$25"],
  ["$18"],
  ["$22"],
  ["$10"]
];
var merged = [].concat.apply([], arrays);

console.log(merged);

Example 5: flatten an array in javascript

// Although this now may be an older version of how to faltten an 
// array of arrays. I still want to post it so some may have an understanding 
// of how it works

function falltenArray(arr) {
  
  let result = [...arr];
  let flattened = false;
  let counter = 0;
  
  while (flattened === false){
	// checks to see if the element at the counter index is an array
      if (Array.isArray(result[counter])){
        // unpacks the current array element back into the array
        result.splice(counter, 1, ...result[counter]);
        // if so the counter should start at the beginning of the array
        counter = 0;
        
      } else {
        counter += 1;
      }

      if (counter === result.length){
        flattened = true;
      }
  }
  
  return result;
}

Example 6: flatten array object javascript

var flattenArray = function(data) {
	return data.reduce(function iter(r, a) {
		if (a === null) {
			return r;
		}
		if (Array.isArray(a)) {
			return a.reduce(iter, r);
		}
		if (typeof a === 'object') {
			return Object.keys(a).map(k => a[k]).reduce(iter, r);
		}
		return r.concat(a);
	}, []);
}
console.log(flattenArray(data))

//replace data with your array