从数组中删除重复项并替换

Question

I have an array of elements:

arr = ["one", "two", "three", "one", "two", "one"]

I want to replace duplicates with empty strings in array:

output= ["", "", "three", "", "", ""]

Here is my code:

let obj = {}

for(let i=0; i<arr.length; i++) {
   let a = arr[i];
   if(obj[a]) obj[a]+=1
   else obj[a]=1
}

let output = []

for(let i=0; i<arr.length; i++) {
   output[i] = obj[arr[i]] > 1 ? "" : arr[i];
}

Is this a better approach or is there a way to improve the performance?

Answer 1

You can simplify your code using reduce and map , but there aren't really any optimizations that could be made.

 let arr = ["one", "two", "three", "one", "two", "one"]; let freq = arr.reduce((acc,curr)=>(acc[curr] = (acc[curr] || 0) + 1, acc), {}); let res = arr.map(x=>freq[x] === 1? x: ''); console.log(res);

Answer 2

In your ternary operator you forgot to assign the output array to expected value so it should be

 output[i] = objx[arr[i]] > 1 ? output[i]="" : output[i]=arr[i]

 arr = ["one", "two", "three", "one", "two", "one"] obj = {} for(let i=0; i<arr.length; i++) { let a = arr[i]; if(obj[a]) obj[a]+=1 else obj[a]=1 } let output = [] for(let i=0; i<arr.length; i++) { output[i] = obj[arr[i]] > 1? output[i]="": output[i]=arr[i] } console.log(output)

Here is a different simpler approach using foreach and map

 arr = ["one", "two", "three", "one", "two", "one"] var obj = {}; arr.forEach(e => { obj[e] = obj[e] || 0 obj[e] = obj[e] + 1 }) res= arr.map(x => obj[x] > 1? "": x) console.log(res)