1、双层循环：
优点：兼容性最好
function unique(arr){
var newarr = [];
for(var i = 0,aLen = arr.length; i<aLen; i++){
for(var j = 0, newLen = newarr.length; j<newLen; j++){
if(arr[i] === newarr[j]){
break;
}
}
if(j === newLen){
newarr.push(arr[i]);
}
}
return newarr;
}
2、标记
function oSort(arr) {
var result = {};
var newArr = [];
for (var i = 0; i < arr.length; i++) {
if (!result[arr[i]]) { // !undefined为true
newArr.push(arr[i])
result[arr[i]] = 1
}
}
return newArr
}
使用indexOf
var array = [1, 1, '1'];
function unique(array) {
var res = [];
for (var i = 0, len = array.length; i < len; i++) {
var current = array[i];
if (res.indexOf(current) === -1) {
res.push(current)
}
}
return res;
}
console.log(unique(array));
使用filter
var array = [1, 2, 1, 1, '1'];
function unique(array) {
var res = array.filter(function(item, index, array){
return array.indexOf(item) === index;
})
return res;
}
console.log(unique(array));
es6 Set
var array = [1, 2, 1, 1, '1'];
function unique(array) {
return Array.from(new Set(array));
//return [...new Set(array)]
}
console.log(unique(array)); // [1, 2, "1"]
es6 Map
function unique (arr) {
const seen = new Map()
return arr.filter((a) => !seen.has(a) && seen.set(a, 1))
}
