The JavaScript exception "can't redefine non-configurable property" occurs when it was attempted to redefine a property, but that property is non-configurable .
TypeError: Cannot modify non-writable property {x} (Edge)
TypeError: can't redefine non-configurable property "x" (Firefox)
TypeError: Cannot redefine property: "x" (Chrome)
It was attempted to redefine a property, but that property is
non-configurable
。
configurable
attribute controls whether the property can be deleted from the object and whether its attributes (other than
writable
) can be changed. Usually, properties in an object created by an
object initializer
are configurable. However, for example, when using
Object.defineProperty()
, the property isn't configurable by default.
Object.defineProperty
Object.defineProperty()
creates non-configurable properties if you haven't specified them as configurable.
var obj = Object.create({});
Object.defineProperty(obj, "foo", {value: "bar"});
Object.defineProperty(obj, "foo", {value: "baz"});
// TypeError: can't redefine non-configurable property "foo"
You will need to set the "foo" property to configurable, if you intend to redefine it later in the code.
var obj = Object.create({});
Object.defineProperty(obj, "foo", {value: "bar", configurable: true});
Object.defineProperty(obj, "foo", {value: "baz", configurable: true});