handler.deleteProperty()
The handler.deleteProperty()
method is a trap for the [[Delete]]
object internal method, which is used by operations such as the delete
operator.
Try it
Syntax
new Proxy(target, {
deleteProperty(target, property) {
}
});
Parameters
The following parameters are passed to the deleteProperty()
method.
this
is bound to the handler.
target
-
The target object.
property
-
The name or
Symbol
of the property to delete.
Return value
The deleteProperty()
method must return a Boolean
indicating
whether or not the property has been successfully deleted.
Description
Interceptions
This trap can intercept these operations:
-
The
delete
operator:delete proxy[foo]
anddelete proxy.foo
Reflect.deleteProperty()
Or any other operation that invokes the [[Delete]]
internal method.
Invariants
If the following invariants are violated, the trap throws a TypeError
when invoked.
- A property cannot be deleted, if it exists as a non-configurable own property of the target object.
Examples
Trapping the delete operator
The following code traps the delete
operator.
const p = new Proxy(
{},
{
deleteProperty(target, prop) {
if (!(prop in target)) {
console.log(`property not found: ${prop}`);
return false;
}
delete target[prop];
console.log(`property removed: ${prop}`);
return true;
},
},
);
p.a = 10;
console.log("a" in p); // true
const result1 = delete p.a; // "property removed: a"
console.log(result1); // true
console.log("a" in p); // false
const result2 = delete p.a; // "property not found: a"
console.log(result2); // false
Specifications
Specification |
---|
ECMAScript Language Specification # sec-proxy-object-internal-methods-and-internal-slots-delete-p |
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