Solution
\n\n# Code\njavascript []\n/**\n * @param {Array} arr\n * @param {Function} fn\n * @return {Array}\n */\nvar sortBy = function(arr, fn) {\n    return arr.sort((
\n\n# Code\n```javascript []\n/**\n * @param {Array} arr\n * @param {Function} fn\n * @return {Array}\n */\nvar sortBy = function(arr, fn) {\n    return arr.sort((a, b) => fn(a) - fn(b))\n};\n```
['JavaScript']