var a = [4,2,5,6,3,4,5]
var hashTab = {}
for(let i=0; i<a.length;i++){
if(a[i] in hashTab){
// 什么也不做
}else{
hashTab[ a[i] ] = true
}
}
//hashTab: {4: true, 2: true, 5: true, 6:true, 3: true}
console.log(Object.keys(hashTab)) // ['4','2','5','6','3']
var array=[4,5,4,7,2,4,6,7]
var result=array.sort().reduce((acc,cur)=>{
if(acc[acc.length-1]!==cur){
acc.push(cur)
}
return acc
},[])
console.log(result)
function unique(arr){
var result=[]
arr.map(el=>{
if(result.indexOf(el)===-1){
result.push(el)
}
})
return result
}
var a=[3,5,4,6,5,3,5,6,2]
console.log(unique(a))
