best way to convert array to object with prefix value as key in javascript

Question

I have an array with prefix values

["options_a",
"options_b",
"options_c",
"capable_d",
"capable_e_c"
]

i need the output to be in object format with prefix as key and grouped split string as value

object output format needed
{
"options":["a","b","c"],
"capable":["d","e_c"]
}

it can be done with normal for loop, but is there better way of achieving it with simplified form using es6 functionality.

Thank you.

Answer 1

Reduce the array of the prefixed values. Split the item by underscore ( _ ), and use destructuring to get the key, and an array of value (the value might have multiple items after splitting by underscore). If the accumulator ( acc ) doesn't contain the key, create one with an empty array. Push the value to acc[key] after joining it by underscore.

 const arr = ["options_a","options_b","options_c","capable_d","capable_e_c"] const result = arr.reduce((acc, item) => { const [key, ...value] = item.split('_') if(!acc[key]) acc[key] = [] acc[key].push(value.join('_')) return acc; }, {}) console.log(result)

You can avoid the need to join by using a RegExp to split only by the 1st underscore (see this answer ):

 const arr = ["options_a","options_b","options_c","capable_d","capable_e_c"] const result = arr.reduce((acc, item) => { const [key, value] = item.split(/_(.+)/) if(!acc[key]) acc[key] = [] acc[key].push(value) return acc; }, {}) console.log(result)