将嵌套数组转换为对象

Question

I am trying to use reduce to convert a nested array to an object.

I want to convert var bookprice = [["book1", "$5"], ["book2", "$2"], ["book3", "$7"]];

to

var bookpriceObj = {
    "book1": "$5", 
    "book2": "$2",
    "book3": "$7"
};

here is what I tried

var bookprice = [["book1", "$5"], ["book2", "$2"], ["book3", "$7"]];
bookpriceObj = {};
bookprice.reduce(function(a, cv, ci, arr){
    for (var i = 0; i < arr.length; ++i)
        bookpriceObj [i] = arr[i];

    return bookpriceObj ;
})

but the below result is not the desired result

{
    ["book1", "$5"]
    ["book2", "$2"]
    ["book3", "$7"]
}

Answer 1

Using forEach is shorter

 var bookprice = [["book1", "$5"], ["book2", "$2"], ["book3", "$7"]]; var bookpriceObj = {}; bookprice.forEach(e=>bookpriceObj[e[0]] = e[1]); console.log(bookpriceObj) 

Answer 2

You can use reduce with Array Destructoring.

    bookpriceObj = bookprice.reduce((a, [b, c]) => (a[b] = c, a), {});

Here's what's happening:

• a is the accumulator which has an initial value of the final parameter passed to reduce . The last value we pass is {} so it's an object
• Array Destructoring can immediately assign values in an array to variables. ae [a, b] = ["one", "two"] assigns a with a value of "one" and b with a value of "two"
• with each iteration over each item we assign the value of b (ae "book1") as a property on the object( a ) and give it a value equal to c (ae "$2")
• Each iteration of reduce you must return the accumulator( a )
• When the whole thing is finally done, it'll store in bookpriceObj the result!

 var bookprice = [ ["book1", "$5"], ["book2", "$2"], ["book3", "$7"]], bookpriceObj = bookprice.reduce((a, [b, c]) => (a[b] = c, a), {}); console.log(bookpriceObj) 

Answer 3

You need to return an object from the "reducer" AKA the first argument of reduce, and use an empty object as second argument.

 var bookprice = [ ["book1", "$5"], ["book2", "$2"], ["book3", "$7"] ]; var result = bookprice.reduce(function(object, el) { object[el[0]] = el[1] return object; }, {}) console.log(result) 

You don't need a for loop since reduce already iterates over the array.

Answer 4

Using Array.reduce() , Array destructuration , Dynamical keys and Spread operator .

 const bookprice = [ ['book1', '$5'], ['book2', '$2'], ['book3', '$7'], ]; const ret = bookprice.reduce((tmp, [ name, price, ]) => ({ ...tmp, [name]: price, }), {}); console.log(ret); 

Answer 5

You are not returning the accumulated object in your reduce function and the for loop is not necessary.

Try:

const bookprice = [["book1", "$5"], ["book2", "$2"], ["book3", "$7"]];
const nameIndex = 0;
const priceIndex = 1;

const bookPricesObj = bookprice.reduce((prices, bookInfo) => {
    const name = bookInfo[nameIndex];
    const price = bookInfo[priceIndex];

    prices[name] = price;
    return prices;
}, {});

Answer 6

bookprice.reduce((acc, price) => {
  let tmp = {}
  tmp[price[0]] = price[1]
  return Object.assign(acc, tmp)
}, {})

Answer 7

using Array.prototype.reduce to convert a nested array to an object

 var bookprice = [ ["book1", "$5"], ["book2", "$2"], ["book3", "$7"] ]; bookpriceObj = bookprice.reduce(function(acc, cur, i) { acc[cur[0]] = cur[1]; return acc; }, {}) console.log(bookpriceObj);