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JavaScript Symbol Reference

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JavaScript symbol is a data type of primitive data type. The Symbol() function returns the symbol value type. The value returned from Symbol() is unique.

Syntax:

[Symbol.peoperty](string)

Example: JavaScript code to show the working of this function. 

Javascript




// Creating some arrays
const Array1 = [1, 2, 3];
const Array2 = [4, 5, 6];
  
// Calling concat() function
let Array3 = Array1.concat(Array2);
  
// Printing the concatenated array
console.log(Array3);
  
// Calling Symbol.isConcatSpreadable symbol
Array2[Symbol.isConcatSpreadable] = false;
Array3 = Array1.concat(Array2);
  
// Printing the concatenated array
// after calling of Symbol.isConcatSpreadable symbol
console.log(Array3);

Output:

 Array [1, 2, 3, 4, 5, 6]
 Array [1, 2, 3, Array [4, 5, 6]]

The complete list of JavaScript Symbol is listed below:

JavaScript Symbol Constructor: In JavaScript, a constructor gets called when an object is created.

ConstructorDescriptionExample
Symbol()Used to create a symbol object

JavaScript Symbol Properties: A JavaScript property is a member of an object that associates a key with a value.

  • Static Property: A static property is a property that has the same value for the entire class.

Properties

Description 

Example 

asyncIteratorIt sets an object as async iterable
hasInstanceDetermine if a given constructor object recognizes the object as its instance.
isConcatSpreadableGiven object should be flattened to its array elements while using the Array.prototype.concat() method.
iteratorIt makes an element easier to use in for..of loop
matchIt identifies matching of a Regular Expression to a string
matchAllIt returns Regular Expression that matches the String
replaceReplace the matched substring of a string.
searchReturns the index within a string that matches the regular expression. 
speciesIt is used to create a derived object from a function-valued property 
splitSpecify the method that splits a string at the indices that match a regular expression.
toStringTagCreation of the default string description of an object.
unscopablesSpecify an object value of whose own and inherited property names are excluded from the environment bindings.
  • Instance Properties: An instance property is a property that has a new copy for every new instance of the class.

 Properties

Description

Example

constructorReturn the string constructor function for the object.
descriptionReturn the optional description of the specified symbol objects.

JavaScript Symbol Methods: JavaScript methods are actions that can be performed on objects. There are two types of Symbol methods in JavaScript.

  • Static Method: If the method is called using the symbol class itself then it is called a static method.

 Methods 

Description

Example

for()The Symbol.for() is used to search for the given symbol
keyFor()This key is retrieved from the global symbol registry.
  • Instance Method: If the method is called on an instance of a Symbol then it is called an instance method.
MethodsDescriptionExample
toString()convert the specified symbol object into the string.
valueOf()Return the primitive value of a given symbol object.
@@toPrimitive()Convert a given symbol object to a primitive value.

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Last Updated : 31 May, 2023
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