compare 2 object arrays javascript code example

Example 1: how to compare two arrays javascript

function arraysAreIdentical(arr1, arr2){
    if (arr1.length !== arr2.length) return false;
    for (var i = 0, len = arr1.length; i < len; i++){
        if (arr1[i] !== arr2[i]){
            return false;
        }
    }
    return true; 
}

Example 2: comparing array of objects in javascript

// IN THIS EXAMPLE WE HAVE GROUP INSERTS - DATA TO BE ADDED TO DB
// TO INSERT INTO DB EACH GROUP NAME MUST BE THE MATCHING ID
// CONATCT NAME MUST ALSO BE MATCHING ID
// THE CODE BELOW SHOWS HOW TO TRAVERSE THROGUH TWO ARRAYS AND COMPARE / ADD VALES

const groupInserts = [ { groups: [ 'Chess', 'Science', 'German' ], name: 'Ian Smith' },
  { groups: [ 'Swimming' ], name: 'Jenny Smith' },
  { groups: [ 'Tennis' ], name: 'Susan Jones' },
  { groups: [ 'Coding', 'Science' ], name: 'Judy Davis' } ]

const nameAndIdsFromDB = [ { name: 'Parent_1', id: 1 },
{ name: 'Parent_2', id: 2 },
{ name: 'Ian Smith', id: 99 },
{ name: 'Jenny Smith', id: 100 },
{ name: 'Susan Jones', id: 101 },
{ name: 'Judy Davis', id: 102 } ]

const groupnameAndIdsFromDB = [ { name: 'Debugging', id: 1 },
{ name: 'React', id: 2 },
{ name: 'New record with no people', id: 3 },
{ name: 'New record with people', id: 4 },
{ name: 'Chess', id: 12 },
{ name: 'Science', id: 13 },
{ name: 'German', id: 14 },
{ name: 'Swimming', id: 15 },
{ name: 'Tennis', id: 16 },
{ name: 'Coding', id: 17 } ]

let groupNamesWithIds = [];
groupInserts.forEach(data => {
    if (data.groups) {
         data.groups.map(e => {
                let obj = {};
                obj.group = e;
                obj.name = data.name
                groupNamesWithIds.push(obj);
        })
    }
})


let addedMessageGroupIds = [];
groupNamesWithIds.forEach(data => {
  groupnameAndIdsFromDB.map(e => {
    if (e.name === data.group) {
      addedMessageGroupIds.push({group: data.group, name: data.name, messages_individual_groups_id: e.id})
    }
  })
})

let addedContactIds = [];
addedMessageGroupIds.forEach(data => {
  nameAndIdsFromDB.map(e => {
    if (e.name === data.name) {
      addedContactIds.push({messages_individual_groups_id: data.messages_individual_groups_id, contact_id: e.id, created_at: Date.now()})
    }
  })
})

Example 3: compare arrays javascript

// For regular 1D array
const array1 = [1,2,3,4]
const array2 = [1,2,3,4]

array1.join() === array2.join()
// '1,2,3,4' === '1,2,3,4'

// For anything more complex
const array3 = [1,2,3,[1,2,3]]
const array4 = [1,2,3,[1,2,3]]

JSON.stringify(array3) === JSON.stringify(array4)

Example 4: javascript check if two arrays of objects have same elements

var isEqual = function (value, other) {

	// Get the value type
	var type = Object.prototype.toString.call(value);

	// If the two objects are not the same type, return false
	if (type !== Object.prototype.toString.call(other)) return false;

	// If items are not an object or array, return false
	if (['[object Array]', '[object Object]'].indexOf(type) < 0) return false;

	// Compare the length of the length of the two items
	var valueLen = type === '[object Array]' ? value.length : Object.keys(value).length;
	var otherLen = type === '[object Array]' ? other.length : Object.keys(other).length;
	if (valueLen !== otherLen) return false;

	// Compare two items
	var compare = function (item1, item2) {

		// Get the object type
		var itemType = Object.prototype.toString.call(item1);

		// If an object or array, compare recursively
		if (['[object Array]', '[object Object]'].indexOf(itemType) >= 0) {
			if (!isEqual(item1, item2)) return false;
		}

		// Otherwise, do a simple comparison
		else {

			// If the two items are not the same type, return false
			if (itemType !== Object.prototype.toString.call(item2)) return false;

			// Else if it's a function, convert to a string and compare
			// Otherwise, just compare
			if (itemType === '[object Function]') {
				if (item1.toString() !== item2.toString()) return false;
			} else {
				if (item1 !== item2) return false;
			}

		}
	};

	// Compare properties
	if (type === '[object Array]') {
		for (var i = 0; i < valueLen; i++) {
			if (compare(value[i], other[i]) === false) return false;
		}
	} else {
		for (var key in value) {
			if (value.hasOwnProperty(key)) {
				if (compare(value[key], other[key]) === false) return false;
			}
		}
	}

	// If nothing failed, return true
	return true;

};