Retrieve JSON or JavaScript property with a string reference

Question

Retrieve JSON or JavaScript property with a string reference

Consider the following JSON array:

_htaItems = [
    {"ID":1,
     "parentColumnSortID":"0",
     "description":"Precondition",
     "columnSortID":"1",
     "itemType":0},
    {"ID":2,
     "parentColumnSortID":"0",
     "description":"Precondition",
     "columnSortID":"1",
    "itemType":0}]

The goal is to update this array by providing the ID, column name, and new value as parameters to a function:

function updateJSON(ID, columnName, newValue)
{
    var i = 0;
    for (i = 0; i < _htaItems.length; i++)
    {
        if (_htaItems[i].ID == ID)
        {
            ?????
        }
    }
}

The main question is how to perform the update. Typically, one could simply assign a new value like so:

 _htaItems[x].description = 'New Value'

However, in this case, the column name is provided as a string.

javascript json

Answer 1

Answer №1

When working with JavaScript, there are two ways to access an object property. The first way is using literal notation:

the.answer = 42;

The second way is using bracketed notation with a string for the property name:

the["answer"] = 42;

Both of these methods achieve the same result. However, with the bracketed notation, you can use any expression that resolves to a string inside the brackets. This allows for more flexibility in setting object properties. For example:

x = "answer";
the[x] = 42;

x = "ans";
y = "wer";
the[x + y] = 42;

function foo() {
    return "answer";
}
the[foo()] = 42;

All of the above statements will set the answer property of the object the to 42.

If the value of description cannot be hardcoded and is passed from another source, you can utilize bracketed notation like this:

s = "description"; 
_htaItems[x][s] = 'New Value';

Answer 2

When working with JavaScript, there are two ways to access an object property. The first way is using literal notation:

the.answer = 42;

The second way is using bracketed notation with a string for the property name:

the["answer"] = 42;

Both of these methods achieve the same result. However, with the bracketed notation, you can use any expression that resolves to a string inside the brackets. This allows for more flexibility in setting object properties. For example:

x = "answer";
the[x] = 42;

x = "ans";
y = "wer";
the[x + y] = 42;

function foo() {
    return "answer";
}
the[foo()] = 42;

All of the above statements will set the answer property of the object the to 42.

If the value of description cannot be hardcoded and is passed from another source, you can utilize bracketed notation like this:

s = "description"; 
_htaItems[x][s] = 'New Value';

Answer 3

Answer №2

_htaItems[x][columnName] = 'Updated Content'; Was that not what you meant?

Answer 4

_htaItems[x][columnName] = 'Updated Content'; Was that not what you meant?

Answer 5

Answer №3

To update the value of a specific property, use

_htaItems[i][columnName] = newValue;

. This will modify the value assigned to the key indicated by columnName.

Answer 6

To update the value of a specific property, use

_htaItems[i][columnName] = newValue;

. This will modify the value assigned to the key indicated by columnName.

Answer 7

Answer №4

To successfully assign the new value to a specific column, make sure to utilize square bracket notation in the same way you did for array indexing:

_htaItems[i][columnName] = newValue;

Answer 8

To successfully assign the new value to a specific column, make sure to utilize square bracket notation in the same way you did for array indexing:

_htaItems[i][columnName] = newValue;

Retrieve JSON or JavaScript property with a string reference

Answer №1

Answer №2

Answer №3

Answer №4

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