CODEWITHSUNDEEP
javascriptarrays
akila arasan
akila arasan

Reputation: 747

Insert two consecutive elements in array at specific Index in Javascript

I have two arrays like this,

var firstArray = ['one','two','three','four','five','six','seven'];
var secondArray =['1','2','3','4','5','6','7','8'];

I have to insert second array elements into first array like this,

var combinedArray =['one','two','three','1','2','four','five','six','3','4','seven','5','6','7','8']

I know that I could splice and insert at specific index for one element. However I am confused how exactly to achieve this pattern. Could any one help me out with this?

Upvotes: 3

Views: 465

Answers (4)

Thomas
Thomas

Reputation: 12687

a more granular approach:

var firstArray = ['one','two','three','four','five','six','seven'];
var secondArray =['1','2','3','4','5','6','7','8'];

var combinedArray = flatten(zip(
  toGroupsOf(3, firstArray), 
  toGroupsOf(2, secondArray)
));

console.log(combinedArray);


//a the utilities for that

function isUint(value){
  return value === (value >>> 0)
}

function toGroupsOf(length, arrayOrString){
  if( !isUint(length) || !length  ) 
    throw new Error("invalid length " + JSON.stringify(length));
  
  return Array.from(
    { length: Math.ceil(arrayOrString.length / length) }, 
    (v,i) => arrayOrString.slice(i*length, (i+1)*length)
  );
}

function zip(...arraysOrStrings){
  var numColumns = arraysOrStrings.length,
      lengths = arraysOrStrings.map(item => (item && +item.length) || 0),
      x=0, y=0;
  return Array.from(
    { length: lengths.reduce((a,b)=>a+b, 0) },
    function(v,i){
      for(var safety = numColumns+1; safety--;){
        if(y < lengths[x])
          return arrays[x++][y];
        else if(++x >= numColumns)
          x=0, ++y;
      }
      throw new Error("something went wrong, this line should have never been reached");
    }
  )
}

function flatten(array){
  return [].concat.apply([], array);
}

Upvotes: 0

Nenad Vracar
Nenad Vracar

Reputation: 122155

You can create two variables i and j and increment first one by 3 that you will use to slice first array and increment the second one by 2 and you will use that one to slice second array. If the i + 3 > a.length you will concat rest of elements in b array to result.

var a = ['one','two','three','four','five','six','seven'];
var b = ['1','2','3','4','5','6','7','8'];
var r = [], i = 0, j = 0

while(i < a.length) {
  r.push(...a.slice(i, i + 3), ...b.slice(j, i + 3 < a.length ? j + 2 : b.length))
  i += 3, j += 2
}

console.log(r)

Upvotes: 0

Nina Scholz
Nina Scholz

Reputation: 386883

You could use a pattern for the chunks and slice the wanted length for a new array.

var firstArray = ['one', 'two', 'three', 'four', 'five', 'six', 'seven'],
    secondArray = ['1', '2', '3', '4', '5', '6', '7', '8'],
    data = [firstArray, secondArray],
    pattern = [3, 2],
    result = [],
    i = 0,
    l = data.reduce(function (r, a) { return Math.max(r, a.length); }, 0);

while (i < l) {
    pattern.forEach(function (a, j) {
        result = result.concat(data[j].slice(i * a, (i + 1) * a));
    });
    i++;
}

console.log(result);
.as-console-wrapper { max-height: 100% !important; top: 0; }

Upvotes: 1

Bunnynut
Bunnynut

Reputation: 1328

You can actually splice more than one item:

firstArray.splice(3, 0, "1", "2");

Upvotes: 0

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