javascript - how to change the array format to the object format?

Question

How to use javascript to change the array to the object format? Thanks!

[ "16-282", "16-311", "16-320", "17-275", "17-276" ]

object format：</p>

[{
    id: 16,
    Options: [282, 311, 320],
  },
  {
     id: 17,
     Options: [275, 276],
  }]

My Code:

test() {
  var option = ["16-282", "16-311", "16-320", "17-275", "17-276"];


  var finalResult = option.map((item, index) => ({id: item, Options: item,  }));
  console.log(finalResult);
},

标签： javascript

Answer 1

Lets start with your code:

var finalResult = option.map((item, index) => ({id: item, Options: item,  }));

Here you are using .map. It will return an array of n length with parsed output.

---

Based on your output, you need to group the values based on part that is before -. This can be done in many ways, but I'll use for as its easy to understand:

Idea:

• Create an object to hold groups. Object and not array as Objects are key-value pair structure. So your groupId would be key and value will be the value to store.
• Now loop over the option array.
  • For every iteration, split item using hyphen(-). First part is your key and second is your value.
  • Check if this key exists in group. If yes, push current value to the Options array.
  • If it does not exists, initialize it with default structure: { id: groupKey, Options: [ groupValue ] }

Sample:

var option = ["16-282", "16-311", "16-320", "17-275", "17-276"];

var groups = {};

for (var i = 0; i< option.length; i++) {
  var parts = option[i].split('-');
  var groupKey = parts[0];
  var groupValue = parts[1];
  
  // Check if the groupKey exists in group
  if (groups[ groupKey ] !== undefined) {
    groups[ groupKey ].Options.push(groupValue)
  } else {
    groups[ groupKey ] = { id: groupKey, Options: [ groupValue ] }
  }
}

console.log(groups)

---

Now that you have groups, you just need to loop over this object and make an array.

An accumulation of above grouping idea and creating array is as follows:

var option = ["16-282", "16-311", "16-320", "17-275", "17-276"];

const groups = option.reduce((acc, item) => {
  const [ id, value ] = item.split('-');
  acc[ id ] = acc[ id ] || { id, Options: [ ]};
  acc[ id ].Options.push(value);
  return acc;
}, {});

const result = Object.values(groups);
console.log(result)

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