Insert two consecutive elements in array at specific Index in Javascript

Question

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?

Answer 1

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); 

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Answer 2

您实际上可以拼接多个项目：

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

Answer 3

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) 

Answer 4

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); }