JavaScript Reflect has() Method

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JavaScript Reflect.has() method in JavaScript is used to check whether the property exists in an object or not. It works like the in operator as a function.

Syntax:

Reflect.has(target, propertyKey)

Parameters: This method accepts two parameters as mentioned above and described below:

target: This parameter is the target object and it looks for the property.
propertyKey: This parameter is the name of the property to be checked.

Return value: This method returns a Boolean value which indicates if the target has the property.

Exceptions: A TypeError is an exception given as the result when the target is not an object.

The below examples illustrate the Reflect.has() method in JavaScript:

Example 1: In this example, we will check if the object has the property or not using the Reflect.has() method in JavaScript.

javascript

const object1 = { 
    property1: 434 
}; 
  
console.log(Reflect.has(object1, 'property1')); 
console.log(Reflect.has(object1, 'property2')); 
console.log(Reflect.has(object1, 'toString')); 
  
let x = { foo: 1 }; 
console.log(Reflect.has(x, 'foo')); 
console.log('foo' in x); 
console.log(Reflect.has(x, 'bar')); 
console.log('bar' in x);

Output:

true
false
true
true
true
false
false

Example 2: In this example, we will check if the object has the property or not using the Reflect.has() method in JavaScript.

javascript

// Returns true for properties in 
// the prototype chain  
console.log(Reflect.has({ x: 0 }, 'toString')); 
  
// Proxy with .has() handler method 
let obj = new Proxy({}, { 
    has(t, k) { return k.startsWith('zambiatek') } 
}); 
console.log(Reflect.has(obj, 'zambiatek')); 
console.log(Reflect.has(obj, 'geekforgeek')); 
  
const val1 = { foo: 123 } 
const val2 = { __proto__: val1 } 
const val3 = { __proto__: val2 } 
  
// The prototype chain is: c -> b -> a 
console.log(Reflect.has(val3, 'foo'));

Output:

true
true
false
true

Supported Browsers: The browsers supported by JavaScript Reflect.has() Method are listed below:

Google Chrome 49 and above
Edge 12 and above
Firefox 42 and above
Opera 36 and above
Safari 10 and above

We have a complete list of Javascript Reflects methods, to check those go through the JavaScript Reflect Reference article.

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