1
targetId = [313,309,307,318,317]

data={
313:[{time:..., value:...},
{time:..., value:...},
{time:..., value:...},
{time:..., value:...},
],
303:[{time:..., value:...},
{time:..., value:...},
{time:..., value:...},
{time:..., value:...},
],
309:[{time:..., value:...},
{time:..., value:...},
{time:..., value:...},
{time:..., value:...},
],
307:[{time:..., value:...},
{time:..., value:...},
{time:..., value:...},
{time:..., value:...},
],
322:[{time:..., value:...},
{time:..., value:...},
{time:..., value:...},
{time:..., value:...},
],
318:[{time:..., value:...},
{time:..., value:...},
{time:..., value:...},
{time:..., value:...},
],
317:[{time:..., value:...},
{time:..., value:...},
{time:..., value:...},
{time:..., value:...},
],
311:[{time:..., value:...},
{time:..., value:...},
{time:..., value:...},
{time:..., value:...},
]
}

Can someone help me please. So I need to loop through data object and if data property match with one of number from targetId list then I need to extract all values from that property and store them in separate list.

for (let i = 0; i < targetId.length; i++) {
if(targetId[i] === data.[property])
separateList.push(data.[property].value)
}

I guess something like this should maybe do it but need to somehow add looping through object

userXYZ
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  • Either `map` or `flatMap` depending on the output you need: `targetId.flatMap(k => data[k])` – adiga Feb 04 '21 at 10:25

1 Answers1

2

Array of arrays

You can Array#map over targetId and pick items from data and extract values as an array again using .map():

targetId.map(
  id => data[id].map(({value}) => value)
);

Demo:

const targetId = [313,309,307,318,317]

const data = {
  313:[
    {time:3131, value:3131},
    {time:3132, value:3132},
    {time:3133, value:3133},
    {time:3134, value:3134},
  ],
  303:[
    {time:3031, value:3031},
    {time:3032, value:3032},
    {time:3033, value:3033},
    {time:3034, value:3034},
  ],
  309:[
    {time:3091, value:3091},
    {time:3092, value:3092},
    {time:3093, value:3093},
    {time:3094, value:3094},
  ],
  307:[
    {time:3071, value:3071},
    {time:3072, value:3072},
    {time:3073, value:3073},
    {time:3074, value:3074},
  ],
  322:[
    {time:3221, value:3221},
    {time:3222, value:3222},
    {time:3223, value:3223},
    {time:3224, value:3224},
  ],
  318:[
    {time:3181, value:3181},
    {time:3182, value:3182},
    {time:3183, value:3183},
    {time:3184, value:3184},
  ],
  317:[
    {time:3171, value:3171},
    {time:3172, value:3172},
    {time:3173, value:3173},
    {time:3174, value:3174},
  ],
  311:[
    {time:3111, value:3111},
    {time:3112, value:3112},
    {time:3113, value:3113},
    {time:3114, value:3114},
  ]
}

const result = targetId.map(
  id => data[id].map(({value}) => value)
);
console.log(result);

Single array

If you want a single array of values, not an array of array of values, then use Array#flatMap:

targetId.flatMap(
  id => data[id].map(({value}) => value)
);

Demo:

const targetId = [313,309,307,318,317]

const data = {
  313:[
    {time:3131, value:3131},
    {time:3132, value:3132},
    {time:3133, value:3133},
    {time:3134, value:3134},
  ],
  303:[
    {time:3031, value:3031},
    {time:3032, value:3032},
    {time:3033, value:3033},
    {time:3034, value:3034},
  ],
  309:[
    {time:3091, value:3091},
    {time:3092, value:3092},
    {time:3093, value:3093},
    {time:3094, value:3094},
  ],
  307:[
    {time:3071, value:3071},
    {time:3072, value:3072},
    {time:3073, value:3073},
    {time:3074, value:3074},
  ],
  322:[
    {time:3221, value:3221},
    {time:3222, value:3222},
    {time:3223, value:3223},
    {time:3224, value:3224},
  ],
  318:[
    {time:3181, value:3181},
    {time:3182, value:3182},
    {time:3183, value:3183},
    {time:3184, value:3184},
  ],
  317:[
    {time:3171, value:3171},
    {time:3172, value:3172},
    {time:3173, value:3173},
    {time:3174, value:3174},
  ],
  311:[
    {time:3111, value:3111},
    {time:3112, value:3112},
    {time:3113, value:3113},
    {time:3114, value:3114},
  ]
}

const result = targetId.flatMap(
  id => data[id].map(({value}) => value)
);
console.log(result);

Only existing results

If targetId might have items that aren't in data, then you can Array#filter and then .map()/.flatMap():

targetId
    .filter(id => id in data)
    .map(id => data[id].map(({value}) => value))

Demo:

const targetId = [313,309, 9001, 307,318,317, 42]

const data = {
  313:[
    {time:3131, value:3131},
    {time:3132, value:3132},
    {time:3133, value:3133},
    {time:3134, value:3134},
  ],
  303:[
    {time:3031, value:3031},
    {time:3032, value:3032},
    {time:3033, value:3033},
    {time:3034, value:3034},
  ],
  309:[
    {time:3091, value:3091},
    {time:3092, value:3092},
    {time:3093, value:3093},
    {time:3094, value:3094},
  ],
  307:[
    {time:3071, value:3071},
    {time:3072, value:3072},
    {time:3073, value:3073},
    {time:3074, value:3074},
  ],
  322:[
    {time:3221, value:3221},
    {time:3222, value:3222},
    {time:3223, value:3223},
    {time:3224, value:3224},
  ],
  318:[
    {time:3181, value:3181},
    {time:3182, value:3182},
    {time:3183, value:3183},
    {time:3184, value:3184},
  ],
  317:[
    {time:3171, value:3171},
    {time:3172, value:3172},
    {time:3173, value:3173},
    {time:3174, value:3174},
  ],
  311:[
    {time:3111, value:3111},
    {time:3112, value:3112},
    {time:3113, value:3113},
    {time:3114, value:3114},
  ]
}

const result = targetId
  .filter(id => id in data)
  .map(id => data[id].map(({value}) => value));
console.log(result);
VLAZ
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  • Can you plese help me with next situation: so that data object is comming in my component from this.props and sometimes I get following: data={ 313:[], 303:[], ... } so I get data object with empty arrays how can I check and add if statement to see if those properties 313,303... have empty arrays or not? – userXYZ Feb 04 '21 at 11:32
  • 1
    @Kraki98 what needs to happen if the arrays are empty? If you want to ignore them, then you can use `.filter(id => data[id].length > 0)` before mapping. – VLAZ Feb 04 '21 at 11:34