handler.get()
The handler.get()
method is a trap for the [[Get]]
object internal method, which is used by operations such as property accessors.
Try it
Syntax
js
new Proxy(target, {
get(target, property, receiver) {
}
});
Parameters
Return value
The get()
method can return any value.
Description
Interceptions
This trap can intercept these operations:
- Property access:
proxy[foo]
andproxy.bar
Reflect.get()
Or any other operation that invokes the [[Get]]
internal method.
Invariants
If the following invariants are violated, the trap throws a TypeError
when invoked.
- The value reported for a property must be the same as the value of the corresponding target object property if the target object property is a non-writable, non-configurable own data property.
-
The value reported for a property must be undefined if the corresponding target
object property is a non-configurable own accessor property that has
undefined
as its[[Get]]
attribute.
Examples
Trap for getting a property value
The following code traps getting a property value.
js
const p = new Proxy(
{},
{
get(target, property, receiver) {
console.log(`called: ${property}`);
return 10;
},
},
);
console.log(p.a);
// "called: a"
// 10
The following code violates an invariant.
js
const obj = {};
Object.defineProperty(obj, "a", {
configurable: false,
enumerable: false,
value: 10,
writable: false,
});
const p = new Proxy(obj, {
get(target, property) {
return 20;
},
});
p.a; // TypeError is thrown
Specifications
Specification |
---|
ECMAScript Language Specification # sec-proxy-object-internal-methods-and-internal-slots-get-p-receiver |
Browser compatibility
BCD tables only load in the browser