const array = []; for (let i = 0; i < 2000; i++) { array.push({ key: i, prop: Math.floor(Math.random() * 10000) }) } const hashmap = array.reduce((mapper, next) => ({ ...mapper, [next.key]: next }), {}); function findInArray (key) { const index = bs(array, key, function(element, needle) { return element.key - needle; }); return index > 0 ? array[index] : undefined; } function findInHashMap (key) { return hashmap[key] || undefined; } function findInArrayByPolling (key) { for (let i = 0, len = array.length ; i < len; i++) { if (array[i].key === key) { return array[i] } } } function bs(haystack, needle, comparator, low, high) { var mid, cmp; if(low === undefined) low = 0; else { low = low|0; if(low < 0 || low >= haystack.length) throw new RangeError("invalid lower bound"); } if(high === undefined) high = haystack.length - 1; else { high = high|0; if(high < low || high >= haystack.length) throw new RangeError("invalid upper bound"); } while(low <= high) { // The naive `low + high >>> 1` could fail for array lengths > 2**31 // because `>>>` converts its operands to int32. `low + (high - low >>> 1)` // works for array lengths <= 2**32-1 which is also Javascript's max array // length. mid = low + ((high - low) >>> 1); cmp = +comparator(haystack[mid], needle, mid, haystack); // Too low. if(cmp < 0.0) low = mid + 1; // Too high. else if(cmp > 0.0) high = mid - 1; // Key found. else return mid; } // Key not found. return ~low; }