handler.get()
The handler.get()
method is a trap for getting a property
value.
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Syntax
const p = new Proxy(target, {
get: function(target, property, receiver) {
}
});
Parameters
The following parameters are passed to the get()
method. this
is bound to the handler.
target
- The target object.
property
- The name or
Symbol
of the property to get. receiver
- Either the proxy or an object that inherits from the proxy.
Return value
The get()
method can return any value.
Description
The handler.get()
method is a trap for getting a property
value.
Interceptions
This trap can intercept these operations:
- Property access:
proxy[foo]
andproxy.bar
- Inherited property access:
Object.create(proxy)[foo]
Reflect.get()
Invariants
If the following invariants are violated, the proxy will throw a
TypeError
:
- 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.
const p = new Proxy({}, {
get: function(target, property, receiver) {
console.log('called: ' + property);
return 10;
}
});
console.log(p.a); // "called: a"
// 10
The following code violates an invariant.
const obj = {};
Object.defineProperty(obj, 'a', {
configurable: false,
enumerable: false,
value: 10,
writable: false
});
const p = new Proxy(obj, {
get: function(target, property) {
return 20;
}
});
p.a; // TypeError is thrown
Specifications
Browser compatibility
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