Question 386357 in Javascript Question posted in
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Javascript – Making a multiplication table as 2 arrays

I am currently trying to make a multiplication table of 10 with 2 nested for loops
It works somewhat, but the first indices aren’t working as intended:

my code:


var multiplicationTable = []
for (var i = 1; i <= 10; i++) {
    multiplicationTable[i] = [i]
     for (var j = 1; j <= 10; j++) {
        multiplicationTable[i][j] = i*j
    }
}

result:


[1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

[2, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20]

[3, 3, 6, 9, 12, 15, 18, 21, 24, 27, 30]

[4, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40]

[5, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50]

[6, 6, 12, 18, 24, 30, 36, 42, 48, 54, 60]

[7, 7, 14, 21, 28, 35, 42, 49, 56, 63, 70]

[8, 8, 16, 24, 32, 40, 48, 56, 64, 72, 80]

[9, 9, 18, 27, 36, 45, 54, 63, 72, 81, 90]

[10, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100]

I don’t understand why the first index of each array is the same as the second,
I want to create this without that first index.

Help and how you solved it would be amazing, thank you very much!

Tags:

2

Answers


  1. 0

    Array indexes start at 0. So subtract 1 from i and j to get the appropriate array indexes.

    var multiplicationTable = []
for (var i = 1; i <= 10; i++) {
  multiplicationTable[i-1] = []
  for (var j = 1; j <= 10; j++) {
    multiplicationTable[i-1][j-1] = i * j
  }
}

console.log(multiplicationTable);
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  2. 0

    Here is another approach, using Array.map():

    const n=10,res=Array(n).fill(0).map((_,i)=>
  Array(n).fill(0).map((_,j)=>
   (i+1)*(j+1)
))

console.log(JSON.stringify(res));

    The fill(0) is necessary as .map() will not iterate over undefined array elements.

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