access values of an object javascript

Question

I am a beginning in javascript. So i have this data with the basic structure like so...

{
"status": "active",
"experimental": false,
"expansion": {
    "extension": [
        {
            "valueBoolean": true
        }
    ],
    "contains": [
        {
            "system": "http://snomed.info/sct",
            "code": "8989938493",
            "display": "Acute"
        },
        {
            "system": "http://snomed.info/sct",
            "code": "889080980089",
            "display": "Chronic"
        },
        {
            "system": "http://snomed.info/sct",
            "code": "889080980089",
            "display": "Fragile"
        }
    ]
}

}

I want to iterate over "contains" and put the values of "display" in an array so i can use it in a react component. I am currently struggling to achieve that. Any help will be appreciated. Thanks in advance.

And the actual problem is? The title talks about accessing a property of an object? In the question its "how to iterate an array" + "how to access a property...". — Andreas, Aug 19 '21 at 15:04

score 2 · Answer 1 · answered Aug 19 '21 at 15:07

You can use the map function to transform an array:

const myObject = {
"status": "active",
"experimental": false,
"expansion": {
    "extension": [
        {
            "valueBoolean": true
        }
    ],
    "contains": [
        {
            "system": "http://snomed.info/sct",
            "code": "8989938493",
            "display": "Acute"
        },
        {
            "system": "http://snomed.info/sct",
            "code": "889080980089",
            "display": "Chronic"
        },
        {
            "system": "http://snomed.info/sct",
            "code": "889080980089",
            "display": "Fragile"
        }
    ]
}
}

const arr = myObject.expansion.contains.map(({display})=>display)
console.log(arr)

Thank you for the response. Your code works fine here but throws " Server Error TypeError: Cannot read property 'expansion' of undefined" in my code. Console.log(data) of the fetched data works fine. don't know what the issue is. — user13171920, Aug 19 '21 at 15:50

score 0 · Accepted Answer · answered Aug 19 '21 at 15:05

0

let res = [];
const obj = {
"status": "active",
"experimental": false,
"expansion": {
    "extension": [
        {
            "valueBoolean": true
        }
    ],
    "contains": [
        {
            "system": "http://snomed.info/sct",
            "code": "8989938493",
            "display": "Acute"
        },
        {
            "system": "http://snomed.info/sct",
            "code": "889080980089",
            "display": "Chronic"
        },
        {
            "system": "http://snomed.info/sct",
            "code": "889080980089",
            "display": "Fragile"
        }
    ]
}
}

obj.expansion.contains.forEach(el => res.push(el.display));

console.log(res)

answered Aug 19 '21 at 15:05

LeeLenalee

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Why the re-invention of `Array.prototype.map()`? – Andreas Aug 19 '21 at 15:08
Thank you for the response. Your code works fine here but throws " Server Error TypeError: Cannot read property 'expansion' of undefined" in my code. Console.log(data) of the fetched data works fine. don't know what the issue is. – user13171920 Aug 19 '21 at 15:50

access values of an object javascript

2 Answers2