减少无法正常工作？

Question

I'm currently trying to convert an array into an object with the array index as the property of the created object.

Example Array: ['a','b','c']

Expected Object result: {'1':'a','2':'b','3':'c'}

My code is below, it worked when I used map method but when I use the reduce method instead it comes out weird way:

 let sampleData = ['a','b','c']; let convertArrToObjWithIndexProp = (arr) => { /*let res = {}; arr.map((v,k)=> { res[k+1]=v; }) return res;*/ //--> this outputs {'1':'a','2':'b','3':'c'} return arr.reduce((iv,cv,i)=>{ return Object.assign(iv,iv[i+1]=cv); },{}); //--> this outputs instead {'0':'c','1':'a','2':'b','3':'c'} } console.log(convertArrToObjWithIndexProp(sampleData)); 

Can someone explain to me why its coming out like that?

Also is using reduce better than using map?

Answer 1

The problem is that result of this expression: iv[i+1]=cv is cv , which you then Object.assign to the accumulator. You could make it simpler with a simple assignment:

 let sampleData = ['a','b','c']; let convertArrToObjWithIndexProp = (arr) => arr.reduce((iv,cv,i) => (iv[i+1] = cv, iv),{}); console.log(convertArrToObjWithIndexProp(sampleData)); 

Answer 2

Don't use Object.assign . Just update your object and return it.

 let sampleData = ['a','b','c']; let convertArrToObjWithIndexProp = (arr) => { return arr.reduce((iv,cv,i)=>{ iv[i+1]=cv return iv },{}); } console.log(convertArrToObjWithIndexProp(sampleData)); 

Answer 3

You can achieve it by doing this

let array = ['a','b','c'];
return array.reduce((acc, currentValue, index) => {
    const key= index + 1;
    acc[key] = currentValue;
    return acc;
}, {});

Output will be like this

{
  "1": "a",
  "2": "b",
  "3": "c"
}

Answer 4

 var arr = ['a','b','c']; var result = arr.reduce((obj, val, index) => { obj[index + 1] = val; return obj; }, {}); console.log(result); 

Answer 5

I'd do it with Array.reduce function, and Object computed property.

 var sampleData = ['a', 'b', 'c']; console.log(sampleData.reduce((mem, curr, index) => ({ ...mem, [index + 1]: curr }), {}))