CODEWITHSUNDEEP
javascriptfor-loop
codebarz
codebarz

Reputation: 327

Avoiding nested for loop without using array methods

Say I have two arrays of objects. Like

var name = [
    { name : 'john' },
    { name : 'doe' }
]
var name2 = [
    { name : 'john' },
    { name : 'does' }
]

And I want to check if a name in the first array is the same as a name in the second array and return a response. I will do this below

for(var i = 0; i < name.length; i++) {
    for(var j = 0; j < name2.length; j++) {
        if(name[i].name === name2[j].name) {
            console.log('good')
        } else {
            console.log('bad');
        }
    }
}

The above code would give the following result

good
bad 
bad
bad

How do I achieve the same result without using a nested for loop?

I tried using forEach to loop through at once. Like

name.forEach(function(value, index) {
    if(value.name === name2[index].name) {
        console.log('good');
    }
    console.log('bad')
});

But this doesn't work and gives issues when they are arrays of different lengths.

All my research lead to using filter, map, reduce... methods. I want to achieve this using just for loops only. Thanks.

Upvotes: 3

Views: 2459

Answers (4)

Priyesh Diukar
Priyesh Diukar

Reputation: 2142

You can try the following code:

var arr = [
    { name : 'john' },
    { name : 'doe' }
]
var arr2 = [
    { name : 'john' },
    { name : 'peter' },
    { name : 'doe' }
]

var i = 0, length = Math.min(arr.length, arr2.length);

for(i; i < length; i++) {
    if(arr[i].name === arr2[i].name) {
            console.log('good')
        } else {
            console.log('bad');
     }
}

Upvotes: 1

adiga
adiga

Reputation: 35222

From

I tried using forEach. But this doesn't work and gives issues when they are arrays of different lengths.

I gather you want to compare both arrays irrespective of the length. So, you can get the maximum length out of 2 arrays using Math.max. Then, loop through and check if the 2 arrays have the same value at each index

The condition name1[i] && name2[i] checks for undefined when the smaller array doesn't have a value at the specified index.

var name1 = [
    { name : 'john' },
    { name : 'doe' }
]
var name2 = [
    { name : 'john' },
    { name : 'does' },
    { name : 'jane' }
]

var maxLength = Math.max(name1.length, name2.length);

for (var i = 0; i < maxLength; i++) {
  if (name1[i] && name2[i] && name1[i].name === name2[i].name)
    console.log("good")
  else
    console.log("bad")
}

Upvotes: 2

Flo
Flo

Reputation: 986

Another solution using "map" function in order to avoid using nested loops. Am not sure it answers the whole question but hope it helps.

//var search_value = 'john'; // will print 'good'
var search_value = 'doe'; // will print 'bad'

var name1 = [
    { name : 'john' },
    { name : 'doe' }
];

var name2 = [
    { name : 'john' },
    { name : 'does' }
];

var pos1 = name1.map(function(element) { return element.name; }).indexOf(search_value);
var pos2 = name2.map(function(element) { return element.name; }).indexOf(search_value);

var result = (pos1 == pos2) ? 'good' : 'bad';
console.log(result)

Upvotes: 0

Nemanja G
Nemanja G

Reputation: 1850

You dont have to have 2 loops. What you can do is the following: map that array into an object, have this structure for both arrays:

// first array
{
"jhon": 1, //count how many names u have in each array
"otherName": 1
}

// second array
{
"jhon": 1, //count how many names u have in each array
"otherName": 1
}

and then just compare those 2 arrays. Much faster and cleaner imo.

Upvotes: 0

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