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JavaScript - check nested object properties for null/undefined
1 answers
0 points
Let's say I have an object:
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var myObject = {}it gets populated through the course of using the app, for example:
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var myObject = {2
name: 'John',3
metadata: {4
type: 'json',5
},6
};At another place in the code I want to check if myObject.metadata.type exists.
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if (myObject.metadata.type) {2
// do something3
}If it doesn't exists, the code will cause an error.
Also if myObject.metadata is undefined, myObject.metadata.type of course is undefined too.
That means I need to check it like this:
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if (myObject.metadata) {2
if (myObject.metadata.type) {3
// do something4
}5
}I don't think it is efficient way to check this, since the bigger objects are, the worse it gets.
Is there a better way to check conditions like this?
1 answer
0 points
1. Using optional chaining (ES 2020+)
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const myObject = {2
name: 'John',3
metadata: {4
type: 'json',5
},6
};7
8
console.log(myObject?.metadata?.type);In dirask snippets you can find some reusable arrow functions:
2. Alternative solution
You can create a custom function:
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function getValue(object, path) {2
return path.reduce(function (value, key) {3
return value == null ? value : value[key];4
}, object);5
}6
7
8
// Usage example:9
10
var myObject = {11
name: 'John',12
metadata: {13
type: 'json',14
},15
};16
17
var metadata = getValue(myObject, ['metadata', 'type']);18
19
console.log(metadata); // json
See also
References
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