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I have two arrays with same length

array1 = [12,13,14,15,16]
array2 = [22,32,45,11,7]

Now I want to pare only the same index value in a for loop in javasacript ex:

array1[0] < array2[0]
array1[1] < array2[1]
array1[2] < array2[2]

and if value of array1[index] is less than array2[index] it return true

I have two arrays with same length

array1 = [12,13,14,15,16]
array2 = [22,32,45,11,7]

Now I want to pare only the same index value in a for loop in javasacript ex:

array1[0] < array2[0]
array1[1] < array2[1]
array1[2] < array2[2]

and if value of array1[index] is less than array2[index] it return true

• javascript
• arrays

Share Improve this question Follow edited Feb 2, 2020 at 18:43 Mihai Alexandru-Ionut 48.4k1414 gold badges105105 silver badges132132 bronze badges asked Mar 1, 2018 at 7:06 Vivek SinghVivek Singh 3311 silver badge66 bronze badges 6

• Are you pletely sure that both array will have ALWAYS the same length ? – Cristian S. Commented Mar 1, 2018 at 7:07
• What is the expected output when paring your array1 and array2? – Lewis Commented Mar 1, 2018 at 7:08
• what is the problem in paring two arrays if they are same lengths? Just put a loop and an if statement inside it – Arpit Solanki Commented Mar 1, 2018 at 7:09
• Yes i am sure it will always have same length – Vivek Singh Commented Mar 1, 2018 at 7:09
• 1 You must try something always and then ask the question over your code. – Marc Commented Mar 1, 2018 at 7:11

 |  Show 1 more ment

7 Answers 7

Sorted by: Reset to default 8

I suppose the output must be a boolean array. For this, you can use map method by passing a callback function.

array1 = [12,13,14,15,16]
array2 = [22,32,45,11,7]

result = array1.map(function(item, i){
  return item < array2[i];
});

console.log(result);

or simply using arrow functions.

array1 = [12,13,14,15,16], array2 = [22,32,45,11,7]
result = array1.map((item, i) => item < array2[i]);
console.log(result);

If you want to return 1 or 0 values you can use + operator in order to force the result to number primitive type.

result = array1.map(function(item, i){
  return + (item < array2[i]);
});

If you want to receive array with boolean values which indicates if values are lower or higher try this:

var result = [];
for(var i = 0; i < array1.length;i++){
    result.push(array1[i] < array2[i]);
}

Try this:

  array1 = [12,13,14,15,16];
  array2 = [22,32,45,11,7];
  for(var x = 0; x < array1.length; x++) {
      if(array1[x] < array2[x]) {
          //do something
      }

  }

If I understood what you mean with your question this is called lexicographical parison and is built-in for arrays in other languages (for example Python or C++).

In Javascript is present for strings, but you've to implement it yourself for arrays with something like

// lexical less-than-or-equal
function lex_leq(a, b) {
    let i = 0, na = a.length, nb = b.length, n = Math.min(na, nb);
    while (i<n && a[i] === b[i]) i++; // skip over equals
    return i === na || (i !== nb && a[i] < b[i]);
}

Other orderings can be puted by similar code or reusing the same implementation... for example (a<b) is the equivalent to !(b<=a).

a1 = [12,13,14,15,16]
a2 = [22,32,45,11,7]
result = a1.map(function(item, i){
return item < a2[i];
});
console.log(result);

Try this solution. This will tell you which index doesn't match.

var array1 = [12,13,14,15,16];
var array2 = [12,13,14,15,34];

function pareArray(arr1, arr2) {
  if(arr1.length !== arr2.length) return false;
  return arr1.reduce(function(acc, val, index) {
    acc.push(val === arr2[index]);
    return acc;
  }, []);
}

var response = pareArray(array1, array2);
console.log(response);

   

 array1 = [12,13,14,15,16]
 array2 = [22,32,45,11,7]
 result = []


array1.map(function(item, i){
       result[i] = item < array2[i];
});

console.log(result);

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