Javascript Nameof Object Property
In C# there is the posibility to get the name of an object property as a string value. nameof(object.myProperty) --> 'myProprty' Can this be done in Javascript/Typescript? Objec
Solution 1:
There is no nameof
operator in Javascript/Typescript. You can creat a function that takes the key of another object and this is checked by the typescript compiler:
function keyOf<T>(o: T, k: keyof T) {
return k
}
let o = { a: 1 }
keyOf(o, 'a'); //ok
keyOf(o, 'b'); //err
Solution 2:
I made a library that fetches the name of a property at runtime, even for types that don't exist at runtime (interfaces or types in TypeScript):
It can be found on NPM here: @fluffy-spoon/name-of
The source code is simple (just a few lines of code): https://github.com/ffMathy/FluffySpoon.JavaScript.NameOf
Usage
import { getPropertyName, getDeepPropertyName } from'@fluffy-spoon/name-of';
interface SomeType {
foo: boolean;
someNestedObject: {
bar: string;
}
}
console.log(getPropertyName<SomeType>(x => x.foo)); //prints "foo"console.log(getPropertyName<SomeType>(x => x.someNestedObject)); //prints "someNestedObject"console.log(getPropertyName<SomeType>(x => x.someNestedObject.bar)); //prints "bar"console.log(getDeepPropertyName<SomeType>(x => x.foo)); //prints "foo"console.log(getDeepPropertyName<SomeType>(x => x.someNestedObject)); //prints "someNestedObject"console.log(getDeepPropertyName<SomeType>(x => x.someNestedObject.bar)); //prints "someNestedObject.bar"
Library source code
In case you don't want to install the NPM package.
function getPropertyNameInternal<T = unknown>(expression: (instance: T) => any, options: {
isDeep: boolean
}) {
let propertyThatWasAccessed = "";
varproxy: any = newProxy({} as any, {
get: function(_: any, prop: any) {
if(options.isDeep) {
if(propertyThatWasAccessed)
propertyThatWasAccessed += ".";
propertyThatWasAccessed += prop;
} else {
propertyThatWasAccessed = prop;
}
return proxy;
}
});
expression(proxy);
return propertyThatWasAccessed;
}
exportfunction getPropertyName<T = unknown>(expression: (instance: T) => any) {
returngetPropertyNameInternal(expression, {
isDeep: false
});
}
exportfunction getDeepPropertyName<T = unknown>(expression: (instance: T) => any) {
returngetPropertyNameInternal(expression, {
isDeep: true
});
}
Solution 3:
Yes, this can be done in Javascript/Typescript. There is a typescript module.
Shamelessly copied from the manual.
nameof(console);
nameof(console.log);
nameof(console["warn"]);
Transforms to:
"console";
"log";
"warn";
There are more nice examples in the manual.
The solution for yours question:
interface IMyObject {
myPropertyOther: string;
}
letmyObject: IMyObject = {
myProperty: 'Hello world'
};
console.log(myObject[nameof<IMyObject>((o) => o.myProperty)]);
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