easy javascript soln.
\nvar getConcatenation = function(nums) {\n    const result = [];\n    for(let i= 0;  i< nums.length; i++) {\n        result[i] = nums[i];\n        result [i + 
```\nvar getConcatenation = function(nums) {\n    const result = [];\n    for(let i= 0;  i< nums.length; i++) {\n        result[i] = nums[i];\n        result [i + nums.length] = nums[i]\n    }\n    return result;\n};\n```
['JavaScript']