數組去重,是前端開發中處理數據經常使用到的方法,也是面試中常會被問到的知識點。下面我將介紹幾種常見的方法,僅作參考!javascript
function unique4(arr) {
var newArr = []
for (var i = 0; i < arr.length; i++) {
if (newArr.indexOf(arr[i]) === -1) {
newArr.push(arr[i])
}
}
return newArr
}
console.log(unique4([1, 1, 2, 3, 5, 3, 1, 5, 6, 7, 4]))
// 結果是[1, 2, 3, 5, 6, 7, 4]
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function unique2(arr) {
var formArr = arr.sort()
var newArr = [formArr[0]]
for (let i = 1; i < formArr.length; i++) {
if (formArr[i] !== formArr[i - 1]) {
newArr.push(formArr[i])
}
}
return newArr
}
console.log(unique2([1, 1, 2, 3, 5, 3, 1, 5, 6, 7, 4]))
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function unique3(arr) {
var obj = {}
var newArr = []
for (let i = 0; i < arr.length; i++) {
if (!obj[arr[i]]) {
obj[arr[i]] = 1
newArr.push(arr[i])
}
}
return newArr
}
console.log(unique2([1, 1, 2, 3, 5, 3, 1, 5, 6, 7, 4]))
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function unique5(arr) {
var newArr = []
for (var i = 0; i < arr.length; i++) {
if (!newArr.includes(arr[i])) {
newArr.push(arr[i])
}
}
return newArr
}
console.log(unique5([1, 1, 2, 3, 5, 3, 1, 5, 6, 7, 4]))
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function unique6(arr) {
var newArr = []
newArr = arr.filter(function(item) {
return newArr.includes(item) ? '' : newArr.push(item)
})
return newArr
}
console.log(unique6([1, 1, 2, 3, 5, 3, 1, 5, 6, 7, 4]))
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function unique10(arr) {
return Array.from(new Set(arr)) // 利用Array.from將Set結構轉換成數組
}
console.log(unique10([1, 1, 2, 3, 5, 3, 1, 5, 6, 7, 4]))
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