CODEWITHSUNDEEP
javascriptfunctional-programming
serkan
serkan

Reputation: 7141

mapping and filtering chaining

The data looks like this

[{time: '09:00', 'level':'x3', 'type':'ae'}
time: '10:00', 'level':'x6', 'type':'fe'}
time: '09:00', 'level':'y3', 'type':'hy'}
time: '11:00', 'level':'z3', 'type':'hy'}]

The result what i would like to get: filter by the time - 09:00, and create splitted arrays for the same kinds.

Example result:

{"levels": [ "x3","y3"],"types": ["ae","hy"]}

I can do this in three function(filter and map) but I would like to chain them. Is it possible in more elegant way?

Thanks in advance.

Upvotes: 2

Views: 1566

Answers (4)

Van-Nostrand
Van-Nostrand

Reputation: 23

this is an old question, but I always advocate for ONLY using reduce when more than one array method is being chained together

const tmp = [
    {time: '09:00', 'level':'x3', 'type':'ae'},
    {time: '10:00', 'level':'x6', 'type':'fe'},
    {time: '09:00', 'level':'y3', 'type':'hy'},
    {time: '11:00', 'level':'z3', 'type':'hy'}
]

const result = tmp.reduce((acc, { time, level, type }) => {
    if (time === '09:00') {
        acc.levels.push(level)
        acc.types.push(type)
    }
    return acc
}, { levels: [], types: [] })

this cuts down on iterations and gives the same result

Upvotes: 0

Milan Rakos
Milan Rakos

Reputation: 1763

var tmp = [{time: '09:00', 'level':'x3', 'type':'ae'},
  {time: '10:00', 'level':'x6', 'type':'fe'},
  {time: '09:00', 'level':'y3', 'type':'hy'},
  {time: '11:00', 'level':'z3', 'type':'hy'}];

var result = {}; result.levels = []; result.types = [];

tmp.filter(data => data.time === '09:00').map(data => {
  result.levels.push(data.level);
  result.types.push(data.type);
});

console.log(result);

Upvotes: 0

Nina Scholz
Nina Scholz

Reputation: 386560

Just filter and map the properties you want and get an object with wanted properties and all values in an array.

var array = [{time: '09:00', 'level':'x3', 'type':'ae'}, {time: '10:00', 'level':'x6', 'type':'fe'},{time: '09:00', 'level':'y3', 'type':'hy'},{time: '11:00', 'level':'z3', 'type':'hy'}],
    result = array.
        filter(a => a.time === '09:00').
        map(({ level, type }) => ({ level, type })).
        reduce((r, o, i) => (Object.keys(o).forEach(k => (r[k] = r[k] || []).push(o[k])), r), {});
    
console.log(result);

Upvotes: 0

ibrahim mahrir
ibrahim mahrir

Reputation: 31682

Note: the result will be an object containing the two arrays. To get that object, you can use reduce like this:

var arr = [
  {time: '09:00', 'level':'x3', 'type':'ae'},
  {time: '10:00', 'level':'x6', 'type':'fe'},
  {time: '09:00', 'level':'y3', 'type':'hy'},
  {time: '11:00', 'level':'z3', 'type':'hy'}
];

var result = arr.filter(o => o.time === '09:00')
                .reduce((acc, o) => {
                    acc.levels.push(o.level);
                    acc.types.push(o.type);
                    return acc;
                }, {levels: [], types: []});
   
console.log(result);

Upvotes: 2

Related Questions