Mutability And Reference VS Privative Types in JavaScript

                                    Mutability && Primitive
                                        && Reference Examples
                                  
                                    ​
                                  
                                      Mutability And Reference VS Privative
                                          Types in JavaScript
                                    
                                      Mutability && Primitive
                                          && Reference Examples
                                    
                                    ​
​Mutability​
                                  
                                    In JavaScript, String
                                        values are immutable, which means that
                                        they cannot be altered once
                                        created.
                                  
                                    For example, the following code:
                                  
                                            1
                                          
                                          var myStr =
                                              "Bob";
                                        
                                            2
                                          
                                          myStr[0] = "J";
                                        
                                            Copied!
                                          
                                    cannot change the value of myStr
                                        to Job, because the contents of myStr
                                        cannot be altered. Note that this does not
                                        mean that myStr
                                        cannot be changed, just that the
                                        individual characters of a string
                                        literal cannot be changed. The only way
                                        to change myStr
                                        would be to assign it with a new string,
                                        like this:
                                  
                                            1
                                          
                                          var myStr =
                                              "Bob";
                                        
                                            2
                                          
                                          myStr = "Job";
                                        
                                            Copied!
                                          
                                      Objects are passed by reference, are
                                          mutable, and can be modified by our
                                          functions:
                                    
                                            1
                                          
                                          function rotateLeft(arr, num)
                                              {
                                        
                                            2
                                          
                                              for (let i = 0; i < num; i++)
                                              {
                                        
                                            3
                                          
                                              let el = arr.pop();
                                        
                                            4
                                          
                                              arr.unshift(el);
                                        
                                            5
                                          
                                              }
                                        
                                            6
                                          
                                          }
                                        
                                            7
                                          
                                          let myArr = [1, 2, 3, 4, 5,
                                              ];
                                        
                                            8
                                          
                                          rotateLeft(myArr, 2);
                                        
                                            9
                                          
                                          console.log(myArr);
                                        
                                            Copied!
                                          
                                    Strings are passed by value, are
                                        immutable, and a new array is
                                        constructed and returned, because it
                                        cannot be changed in place.
                                  
                                            1
                                          
                                          function rotateString(str, num)
                                              {
                                        
                                            2
                                          
                                              return str.slice(num) +
                                              str.slice(0, num);
                                        
                                            3
                                          
                                          }
                                        
                                            4
                                          
                                          ​
                                        
                                            5
                                          
                                          let str =
                                              "foobar";
                                        
                                            6
                                          
                                          let ret = rotateString(str,
                                              3);
                                        
                                            7
                                          
                                          console.log(str);
                                        
                                            8
                                          
                                          console.log(ret);
                                        
                                            Copied!
                                          
                                      Dereferencing
                                    
                                      Arrays
                                    
                                    To dereference an array, use let [var1, var2]
                                        syntax.
                                  
                                            1
                                          
                                          let arr = ['one',
                                              'two',
                                              'three'];
                                        
                                            2
                                          
                                          ​
                                        
                                            3
                                          
                                          let [first] = arr;
                                        
                                            4
                                          
                                          console.log(first);
                                        
                                            Copied!
                                          
                                      Objects
                                    
                                    To dereference attributes from an
                                        object, use let {}
                                        syntax.
                                  
                                      Primitive Data Types in Depth
                                    
                                    ​
​
                                  
                                      Check Out My New Blog:
                                    
                                    ​Web-Dev-Hub
                                          Bryan
                                            best-celery-b2d7c.netlify.app​
                                  
                                    By
                                      Bryan Guner
                                        on
                                      May 27, 2021.
                                  
                                    ​Canonical link​
                                  
                                    Exported from
                                      Medium
                                        on August 31, 2021.

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Contents

Mutability And Reference VS Privative Types in JavaScript

Mutability && Primitive && Reference Examples

Objects are passed by reference, are mutable, and can be modified by our functions:

Dereferencing

Primitive Data Types in Depth

Check Out My New Blog: