1. Refer to answer 1: Use ES6 to add data type Set

A Set is similar to an array, but the values of its members are unique and have no duplicate values.

function uniq(arry) {
    return [...new Set(arry)];
}

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2. Refer to answer 2: Use indexOf

function uniq(arry) {
    var result = [];
    for (var i = 0; i < arry.length; i++) {
        if (result.indexOf(arry[i]) === -1) {
            // If result does not contain arry[I], add it to array
            result.push(arry[i])
        }
    }
    return result;
}
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3. Reference 答案 3: use includes

function uniq(arry) {
    var result = [];
    for (var i = 0; i < arry.length; i++) {
        if(! result.includes(arry[i])) {// If result does not contain arry[I], add it to array
            result.push(arry[i])
        }
    }
    return result;
}
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4. Take advantage of reduce

function uniq(arry) {
    return arry.reduce((prev, cur) = > prev.includes(cur) ? prev : [...prev, cur], []);
}
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5. Refer to answer 5: Use Map


function arrayNonRepeatfy(arr) {
  let hashMap = new Map(a);let result = new Array(a);// The array is used to return the result
  for (let i = 0; i < arr.length; i++) {
    if(hashMap.has(arr[i])) { // Check whether the key exists in the hashMap
      hashMap.set(arr[i], true);  // True indicates that the key is duplicated in the original array, false vice versa
    } else {  // If the key does not exist in the hashMap, add it
      hashMap.set(arr[i], false); result.push(arr[i]); }}return result;
}
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