How to use hasownproperty

hasOwnProperty is a method on the JavaScript built-in object prototype (Object.prototype), which is used to check whether the object's own properties contain the specified property, rather than the properties inherited from its prototype chain. The basic syntax is "obj.hasOwnProperty(prop)".

hasOwnProperty is a method on the JavaScript built-in object prototype (Object.prototype), used to check whether the object's own properties contain the specified property. Rather than inheriting properties from its prototype chain.

The basic syntax is as follows:

obj.hasOwnProperty(prop)

Among them, obj is the object to be checked, and prop is the property name to be checked.

This method returns a Boolean value, true if the object itself contains the property, otherwise false.

For example:

let obj = { a: 1, b: 2 };  
console.log(obj.hasOwnProperty('a')); // true  
console.log(obj.hasOwnProperty('c')); // false

It should be noted that hasOwnProperty only checks the object itself Properties, excluding properties inherited from the prototype chain. If you want to check a property on the prototype chain, you can use obj.__proto__ or Object.getPrototypeOf(obj) to get the prototype object and call the hasOwnProperty method on the prototype object.

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