consecutive-key-value-in-array-of-object.js

/**
     * @desc consecutiveRoleIdsCountListWithIndex:
     *           -> will check if each element is the same as the one before it in the array
     *           -> if yes it will skip that id & increment the repeated count by +1,
     *           -> it will preserve the non-consecutive duplicates also
     *           output : [{"roleId":"5fdf1c022a4b9dea","repeatedCount":2,"index":0},{"roleId":"cb1c0e2f-aabd-303b-8db4-94458cf0c3ca","repeatedCount":1,"index":2},{"roleId":"5fdf1c022a4b9dea","repeatedCount":1,"index":3},{"roleId":"da0384e0-3e89-3df9-9f7f-191e5766d36b","repeatedCount":1,"index":4}]
     * @param arrayList
     * @returns []
     */
function consecutiveRoleIdsCountListWithIndex(arrayList) {
    let roles = [];
    for (let i = 0; i < arrayList.length; i++) {
        let obj = { roleId: null, repeatedCount: 1, index: '' };
        if (i === 0) {
            obj.roleId = arrayList[i]['roleId'];
            obj.index = i
            roles.push(obj);
        } else {
            if (arrayList[i]['roleId'] !== arrayList[i - 1]['roleId']) {
                obj.roleId = arrayList[i]['roleId'];
                obj.index = i;
                roles.push(obj);
            } else {
                let arrLen = roles.length;
                roles[arrLen - 1].repeatedCount = roles[arrLen - 1].repeatedCount + 1;
            }
        }
    }
    return roles;
}

delete_occurance_NthTime.js

//https://stackoverflow.com/a/49144603/9082543
function deleteNth(arr, x) {
  var cache = {};
  return arr.filter(function (n) {
    cache[n] = (cache[n] || 0) + 1;
    return cache[n] <= x;
  });
}
let s = deleteNth([1, 1, 3, 3, 7, 2, 2, 2, 2], 2);
console.log(s);

filterArrayObject.js

const array1 = [ {id:1},{id:2},{id:3} ];
const array2 = [ {id:3} ]

//need to get the object list which are not present in the array2 against array1

let result = array1.filter(a1 => !array2.find(a2 => a2.id === a1.id));

console.log(result)

//[ { id: 1 }, { id: 2 } ]

//for array of strings check
//https://stackoverflow.com/a/33034768

groupingElement

//grouping-elements-in-array-by-multiple-properties
//link: https://codereview.stackexchange.com/questions/37028/grouping-elements-in-array-by-multiple-properties
function groupBy( array , f )
{
  var groups = {};
  array.forEach( function( o )
  {
    var group = JSON.stringify( f(o) );
    groups[group] = groups[group] || [];
    groups[group].push( o );  
  });
  return Object.keys(groups).map( function( group )
  {
    return groups[group]; 
  })
}

var result = groupBy(list, function(item)
{
  return [item.lastname, item.age];
});

remove all elements contained in another array.js

let toRemove = [1,2,3];
let targetArray = [1,2,4,5,6];

targetArray.filter(el=>!toRemove.includes(el));
//[ 4, 5, 6 ]

remove_consecutive_duplicates.js

//https://stackoverflow.com/a/30716969/9082543

let a = [5, 5, 5, 2, 2, 2, 2, 2, 9, 4, 5, 5, 5];

let b = a.filter(function(item, pos, arr){
  // Always keep the 0th element as there is nothing before it
  // Then check if each element is different than the one before it
  return pos === 0 || item !== arr[pos-1];
});

console.log(b)

//output: [ 5, 2, 9, 4, 5 ]

reusableFilter.js

let reusableFilter = (obj, key) => obj.filter(v => v[key] != null);
reusableFilter(arrayObjectList,keyAttribute)

sort array based on another array.js

//https://gist.github.com/ecarter/1423674
/**
 * Sort array of objects based on another array
 */

function mapOrder (array, order, key) {
  
  array.sort( function (a, b) {
    var A = a[key], B = b[key];
    
    if (order.indexOf(A) > order.indexOf(B)) {
      return 1;
    } else {
      return -1;
    }
    
  });
  
  return array;
};


/**
 * Example:
 */

var item_array, item_order, ordered_array;

item_array = [ 
  { id: 2, label: 'Two' }
, { id: 3, label: 'Three' }
, { id: 5, label: 'Five' }
, { id: 4, label: 'Four' }
, { id: 1, label: 'One'}
];

item_order = [1,2,3,4,5];

ordered_array = mapOrder(item_array, item_order, 'id');

sort object by keys.js

//given object will be sorted by the keys 
Object.keys(objectInfo).sort().reduce(function (acc, key) {
			acc[key] = objectInfo[key];
			return acc;
}, {})