JavaScript - 96.66 % better - used char Array instead if Hash Map
```\nvar minWindow = function(s, t) {\n    \n    let arr = new Array(128).fill(0); // Ascii charSet array to store count\n    let result = [-Infinity, Infinity]
```\nvar minWindow = function(s, t) {\n    \n    let arr = new Array(128).fill(0); // Ascii charSet array to store count\n    let result = [-Infinity, Infinity] // result not yet known\n    let missing = t.length; // missing words initially\n    \n    for(let i=0; i < t.length; i++){ // increase the count in arr\n        arr[t.charCodeAt(i)]++\n    }\n     \n    let start = 0;\n    \n    for(let end = 0; end < s.length; end++){ // start from 0 and then expand\n        if(arr[s.charCodeAt(end)] > 0){ // element present in t then decrese missing\n            missing--\n        }\n        \n        arr[s.charCodeAt(end)]-- // if not present in t then make it negative\n        \n        while(missing == 0){ // start decrementing start to check the best option\n             if(result[1]-result[0] > end - start){ // store the best answer always\n                result[1] = end; result[0] = start\n            }\n            \n           \n            arr[s.charCodeAt(start)]++ \n            if(arr[s.charCodeAt(start)] > 0){ // if the char is present in t\n                missing++\n            }\n          \n            start++ \n        }\n        \n        \n    }\n    \n    return result[1] == Infinity ? "" : s.slice(result[0], result[1]+1);\n    \n};
['Array', 'Sliding Window', 'JavaScript']