Arrays, Objects, Loops

Basic JavaScript Notes (Arrays, Objects, Loops))

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                                                            ARRAY METHODS
==============================================================================================================================

                                                          const family = ['Malaika', 'Jahdai'];

arr.push()
==> add to end of array                                   > family.push('Daaimah');
==> mutates length                                        > console.log(family);
==> return length of new array                            ['Malaika', 'Jahdai', 'Daaimah']

arr.unshift()
==> add to front of array                                 > family.unshift('Omeka');
==> mutates length                                        > console.log(family);
==> return length of new array                            ['Omeka', 'Malaika', 'Jahdai', 'Daaimah']

arr.pop()
==> removes last element                                  > family.pop();
==> returns removed element                               > console.log(family);
==> no element is added into method                       ['Omeka', 'Malaika', 'Jahdai']

arr.shift()
==> removes first element                                 > family.shift();
==> returns removed element                               > console.log(family);
==> no element is added into method                       ['Malaika', 'Jahdai']

arr.indexOf()
==> returns index number                                  > family.indexOf('Malaika');
==> returns -1 index if element is not present            > console.log(family);
                                                          0
                                                          
                                                          > family.indexOf('Omeka');
                                                          -1                                                          

arr.includes()
==> returns index number                                  > family.includes('Omeka');
==> returns boolean if element is present                 > console.log(family);
==> strict equality, no type coersion (23 != '23')        false
                                                          
                                                          > family.includes('Malaika');
                                                          > console.log(family);
                                                          true
  
==============================================================================================================================
                                                           OBJECT METHODS
==============================================================================================================================

                                                          const family = {
                                                            firstName: 'Daaimah',
                                                            lastName: 'Tibrey',
                                                            age: 1992, 
                                                            job: 'Engineer',
                                                            friends: ['Omeka', 'Edward','Shannon'],
                                                            hasDriversLicense: true
                                                          };
                                                          
Object Literal
The above with the property:value pairs inside of curly 
brackets. This can be an empty object or contain a 
single property:value pair.

Ordering Properties
The order of the properties typically doesn't matter in
the editor because when it renders in the console it 
will be ordered alphabetically. This also depends upon 
best practices of the project you are working on.
                                                          
Dot Notation                                              > console.log(family.firstName);

                                                          Daaimah

Bracket Notation                                          > console.log(family['lastName']);

                                                          Tibrey
                                                          
Add Property to Object                                    > family.location = ['CA', 'TX'];
                                                          > family['twitter'] = '@DTibrey';
                                                          > console.log(family);
                                                          
                                                          const family = {
                                                            firstName: 'Daaimah',
                                                            lastName: 'Tibrey',
                                                            birthYear: 1992, 
                                                            job: 'Engineer',
                                                            friends: ['Omeka', 'Edward','Shannon'],
                                                            hasDriversLicense: true,
                                                            location: ['CA', 'TX'],
                                                            twitter: '@DTibrey'
                                                          };
                                                          
Add Property that Holds Function as Value                 > family.calcAge = function(birthYear){
                                                              return 2020 - birthYear;
                                                            }
                                                          > console.log(family.calcAge(1991);
                                                          
                                                          28
                                                          
                                                          > console.log(family);
                                                          const family = {
                                                            firstName: 'Daaimah',
                                                            lastName: 'Tibrey',
                                                            birthYear: 1992, 
                                                            job: 'Engineer',
                                                            friends: ['Omeka', 'Edward','Shannon'],
                                                            hasDriversLicense: true,
                                                            location: ['CA', 'TX'],
                                                            twitter: '@DTibrey',
                                                            calcAge: ƒ (birthYear)
                                                          };
                                                          > console.log(family['calcAge'](1992));
                                                          
                                                          28
                                                          
Delete a Property                                         > delete family.calcAge;
==> removes property from object                          > console.log(family);

                                                          const family = {
                                                            firstName: 'Daaimah',
                                                            lastName: 'Tibrey',
                                                            birthYear: 1992, 
                                                            job: 'Engineer',
                                                            friends: ['Omeka', 'Edward','Shannon'],
                                                            hasDriversLicense: true,
                                                            location: ['CA', 'TX'],
                                                            twitter: '@DTibrey',
                                                          };

This
==> equal to the object calling the method                > family.calcAge = function(){
==> using this can be helpful for when the object             return 2020 - this.birthYear;
changes its name, you won't need to go into the new         }
function to change the object name                        > console.log(family);

                                                          const family = {
                                                            firstName: 'Daaimah',
                                                            lastName: 'Tibrey',
                                                            birthYear: 1992, 
                                                            job: 'Engineer',
                                                            friends: ['Omeka', 'Edward','Shannon'],
                                                            hasDriversLicense: true,
                                                            location: ['CA', 'TX'],
                                                            twitter: '@DTibrey',
                                                            calcAge: ƒ ()
                                                          };
                                                          
Dynamically Render a Sentence                            > const family = {
  (str.length used)                                           firstName: 'Daaimah',
                                                              lastName: 'Tibrey',
                                                              birthYear: 1992, 
                                                              job: 'Software Engineer',
                                                              friends: ['Omeka', 'Edward','Shannon'],
                                                              hasDriversLicense: true,
                                                              calcAge: function(){
                                                                return 2020 - this.birthYear;
                                                              },
                                                              getSummary: function(){
                                                                return `${family.firstName} ${family.lastName}
                                                                is a ${family.calcAge()} year old ${family.job}
                                                                and has ${this.hasDriversLicense ? 'a' : 'no'}
                                                                driver's license. She has ${family.friends.length}
                                                                friends, but her sister is ${family.friends[0]}.`;
                                                              }
                                                            }
                                                          > console.log(family.getSummary());
                                                          
                                                          Daaimah Tibrey is a 28 year old Software Engineer 
                                                          and has a driver's license. She has 3 friends, but
                                                          her sister is Omeka.
                                                          
==============================================================================================================================
                                                           FOR LOOP
==============================================================================================================================

For (start var, stop at condition, iteration){stuff}      for (let counterVar; condition; counterVar = counterVar +/- iteration){
                                                            code that we want repeated
                                                          }
                                                          
                                                          > for(let rep = 1; rep <=10; rep = rep+1){
                                                              console.log('This is iteration number: ', rep);
                                                            }
                                                          This is iteration number:  1
                                                          This is iteration number:  2
                                                          This is iteration number:  3
                                                          This is iteration number:  4
                                                          This is iteration number:  5
                                                          This is iteration number:  6
                                                          This is iteration number:  7
                                                          This is iteration number:  8
                                                          This is iteration number:  9
                                                          This is iteration number:  10
                                                          
                                                          > const daaimah = [
                                                              'Daaimah',
                                                              'Tibrey',
                                                              2020 - 1992,
                                                              'Engineer',
                                                              ['Malaika', 'Jahdai'],
                                                            ];

index 5 DNE so, the counter will always count below 5    for (let i = 0; i < daaimah.length ; i++){
                                                            console.log(typeof daaimah[i], daaimah[i])
                                                          }
                                                          
                                                          string Daaimah
                                                          string Tibrey
                                                          number 28
                                                          string Engineer
                                                          object (2) ["Malaika", "Jahdai"]
                                                          
==> Loop Backwards                                        > for (let i = daaimah.length-1; i >=0 ; i--){
                                                              console.log(daaimah[i])
                                                            }
                                                            
                                                          (2) ["Malaika", "Jahdai"]
                                                          Engineer
                                                          28
                                                          Tibrey
                                                          Daaimah
                                                          
==> Nested Loops                                          > for (let exercise = 1; exercise < 4; exercise++) {
                                                              console.log('==> starting exercise ', exercise);
                                                              for (let rep = 1; rep < 6; rep++){
                                                                console.log('lifting weight rep ', rep);
                                                              }
                                                            }
                                                          
                                                          ==> starting exercise  1
                                                          lifting weight rep  1
                                                          lifting weight rep  2
                                                          lifting weight rep  3
                                                          lifting weight rep  4
                                                          lifting weight rep  5
                                                          ==> starting exercise  2
                                                          lifting weight rep  1
                                                          lifting weight rep  2
                                                          lifting weight rep  3
                                                          lifting weight rep  4
                                                          lifting weight rep  5
                                                          ==> starting exercise  3
                                                          lifting weight rep  1
                                                          lifting weight rep  2
                                                          lifting weight rep  3
                                                          lifting weight rep  4
                                                          lifting weight rep  5
                                                          
==> Continue & Break                                      > const stuff = [ 2, {4: 2, 5: 'Hello', 'Daaimah': "Tibrey"},
continue will skip over the condition found                 'string', 'another_string' ];
break will stop after first condition is met              > for (let i = 0; i < stuff.length; i++) {
                                                             if (typeof stuff[i] !== "string") continue;
                                                             console.log(stuff[i], ' is a ', typeof stuff[i]);
                                                            }
                                                          > for (let i = 0; i < stuff.length; i++) {
                                                             if (typeof stuff[i] !== "number") break;
                                                             console.log(stuff[i],'is the first ', typeof stuff[i]);
                                                            }
                                                            
                                                          string  is a  string
                                                          another_string  is a  string
                                                          2 "is the first " "number"

==============================================================================================================================
                                                           WHILE LOOP
==============================================================================================================================
                                                       
start var;                                          let rep = 1;
While (stop condition) {                            while (rep<=5) {
   stuff;                                             console.log(Exercise ${rep} 🏋`);
   iteration;                                         rep++;
}                                                   }
"string literal" is used in console 
                                                    Exercise 1 🏋
                                                    Exercise 2 🏋
                                                    Exercise 3 🏋
                                                    Exercise 4 🏋
                                                    Exercise 5 🏋
                                                    
==> Does not depend on counter                      > let dice = Math.trunc(Math.random() * 6) + 1; 
Math.trunc() used to remove decimal                  while (dice != 6){
Math.random() used to get random number                console.log('You rolled a ', dice);
between 1 and 0                                        dice = Math.trunc(Math.random() * 6) + 1;
                                                       if (dice === 6) console.log("You've got a ", dice);
                                                     }
                                                   You rolled a  2
                                                   You rolled a  5
                                                   You rolled a  1
                                                   You rolled a  2
                                                   You rolled a  5
                                                   You rolled a  3
                                                   You've got a  6