firstRecurringCharacter
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function firstRecurringCharacter(arr) {
let recurringIndex = null, recurringValue = null;
const obj = {}, len = arr.length;
for(let i=0;i < len;i++) {
if(obj[arr[i]] === undefined) {
obj[arr[i]] = i;
}else {
if(recurringIndex === null || obj[arr[i]] < recurringIndex) {
recurringValue = arr[i];
recurringIndex = obj[arr[i]];
}
}
}
return recurringValue;
}
console.log(firstRecurringCharacter([2,5,5,2,3,4,5,6,7]));
JavaScript
INFO