When encountering a TypeError where it is not possible to read the property 'data' of an undefined value, the result returned may be

Question

When encountering a TypeError where it is not possible to read the property 'data' of an undefined value, the result returned may be

How can I retrieve a value when selecting an element from an array that doesn't have an index?

For instance:

var series = [{data: [10]}, {data: []}, {data: []}, {data: []}, {data: [10]}, {data: []}, {data: [10]},
          {data: []}, {data: []}, {data: []}, {data: [10]},{data: []}, {data: []},{data: []}, {data: []},
          {data: [10]},{data: []},{data: []},{data: []},{data: [10]},{data: []}, {data: []}, {data: []}]

var x = series[44].data || null;

console.log(x)

I am still getting an error. Is my use of || null incorrect in this context?

javascript vue.js undefined

Answer 1

Answer №1

If you have organized n, you can sift series by verifying the index in n.

If only data is required, you can apply this method.

var n = [1, 2, 3, 5, 7, 8, 9, 11, 12, 13, 14, 16, 17, 18, 20, 21, 22],
    series = [{ data: [10] }, { data: [] }, { data: [] }, { data: [] }, { data: [10] }, { data: [] }, { data: [10] }, { data: [] }, { data: [] }, { data: [] }, { data: [10] }, { data: [] }, { data: [] }, { data: [] }, { data: [] }, { data: [10] }, { data: [] }, { data: [] }, { data: [] }, { data: [10] }, { data: [] }, { data: [] }, { data: [] } ],
    result = series.filter((_, i) => n.includes(i));

console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 2

If you have organized n, you can sift series by verifying the index in n.

If only data is required, you can apply this method.

var n = [1, 2, 3, 5, 7, 8, 9, 11, 12, 13, 14, 16, 17, 18, 20, 21, 22],
    series = [{ data: [10] }, { data: [] }, { data: [] }, { data: [] }, { data: [10] }, { data: [] }, { data: [10] }, { data: [] }, { data: [] }, { data: [] }, { data: [10] }, { data: [] }, { data: [] }, { data: [] }, { data: [] }, { data: [10] }, { data: [] }, { data: [] }, { data: [] }, { data: [10] }, { data: [] }, { data: [] }, { data: [] } ],
    result = series.filter((_, i) => n.includes(i));

console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 3

Answer №2

Here is an example of how to implement a conditional check:

var x = i < series.length ? series[i].data : null;

Feel free to experiment with this JS bin

Answer 4

Here is an example of how to implement a conditional check:

var x = i < series.length ? series[i].data : null;

Feel free to experiment with this JS bin

Answer 5

Answer №3

Give this code a try

 let numbers = [1,2,3,5,7,8,9,11,12,13,14,16,17,18,20,21,22];
numbers.forEach((num) => {
    let arrays = [{data: [10]}, {data: []}, {data: []}, {data: []}, {data: [10]}, {data: []}, {data: [10]},
          {data: []}, {data: []}, {data: []}, {data: [10]},{data: []}, {data: []},{data: []}, {data: []},
          {data: [10]},{data: []},{data: []},{data: []},{data: [10]},{data: []}, {data: []}, {data: []}]
    let isInRange = num < arrays.length;
    let result = inRange ? arrays[num].data : "out of bounds";
    console.log(result)
});

Answer 6

Give this code a try

 let numbers = [1,2,3,5,7,8,9,11,12,13,14,16,17,18,20,21,22];
numbers.forEach((num) => {
    let arrays = [{data: [10]}, {data: []}, {data: []}, {data: []}, {data: [10]}, {data: []}, {data: [10]},
          {data: []}, {data: []}, {data: []}, {data: [10]},{data: []}, {data: []},{data: []}, {data: []},
          {data: [10]},{data: []},{data: []},{data: []},{data: [10]},{data: []}, {data: []}, {data: []}]
    let isInRange = num < arrays.length;
    let result = inRange ? arrays[num].data : "out of bounds";
    console.log(result)
});

Answer 7

Answer №4

Have you considered creating the variable "series" only once instead of at each iteration? Also, looping on n and using its value to access another array could lead to inconsistencies. If the length of n is greater than the length of series, it may result in the error you mentioned.

Perhaps a better approach would be:

var series = [{data: [10]}, {data: []}, {data: []}, {data: []}, {data: [10]}, {data: []}, {data: [10]},{data: []}, {data: []}, {data: []}, {data: [10]},{data: []}, {data: []},{data: []}, {data: []},{data: [10]},{data: []},{data: []},{data: []},{data: [10]},{data: []}, {data: []}, {data: []}];

series.forEach(serie => console.log(serie.data));

It's important to grasp this fundamental programming concept. Keep exploring and expanding your understanding of these principles :)

Edit

I apologize if I misinterpreted your question. Perhaps you meant something like this:

var x = series[i] || series[i].data
console.log(x)

Does this solution address your issue?

Answer 8

Have you considered creating the variable "series" only once instead of at each iteration? Also, looping on n and using its value to access another array could lead to inconsistencies. If the length of n is greater than the length of series, it may result in the error you mentioned.

Perhaps a better approach would be:

var series = [{data: [10]}, {data: []}, {data: []}, {data: []}, {data: [10]}, {data: []}, {data: [10]},{data: []}, {data: []}, {data: []}, {data: [10]},{data: []}, {data: []},{data: []}, {data: []},{data: [10]},{data: []},{data: []},{data: []},{data: [10]},{data: []}, {data: []}, {data: []}];

series.forEach(serie => console.log(serie.data));

It's important to grasp this fundamental programming concept. Keep exploring and expanding your understanding of these principles :)

Edit

I apologize if I misinterpreted your question. Perhaps you meant something like this:

var x = series[i] || series[i].data
console.log(x)

Does this solution address your issue?

When encountering a TypeError where it is not possible to read the property 'data' of an undefined value, the result returned may be

Answer №1

Answer №2

Answer №3

Answer №4

Edit

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