JavaScript: Remove duplicates from array without using any shortcut methods

let arr = [2, 1, 3, 1, 7, 1, 7, 9, 3];

function removeDuplicates(arr) {
    let obj = {};
    let arrWithNoDuplicates = [];
    for (let i = 0; i < arr.length; i++) {
        obj[arr[i]] = true;
    }

    for (let key in obj) {
        arrWithNoDuplicates.push(key);
    }
    return arrWithNoDuplicates;
}

console.log(removeDuplicates(arr));

Output:
[ '1', '2', '3', '7', '9' ]

Execute above code here