Functions

For these exercises, always return the answer!

function adder(first, second) {
  let theAnswer = first + second;
  return theAnswer;
}

Relational Operators

Symbol	Meaning
===	exactly equals
!==	does not equal
=	assignment
+=	add or concatenate
-=	subtract
*	multiplication
/	division
%	remainder (modulo)
>	greater than
>=	greater than or equal
<	less than
<=	less than or equal

Logical Operators

Symbol	Meaning
!	not
&&	and
||	or

If / Else If / Else

let someNumber = prompt("Pick a number");

if (someNumber < 42) {
  // something
}
else if (someNumber === 42) {
  // another thing
}
else {
  // some default action
}

For Loop - When You Need the Index Value

let nums = [2, 7, 8, 6, 5];
for (let i = 0; i < nums.length; i++) {
  console.log(nums[i]);
}

// 2
// 7
// 8
// 6
// 5

For Loop - Don't Need the Index Value

let nums = [2, 7, 8, 6, 5];
for (let number of nums) {
  console.log(number);
}

// 2
// 7
// 8
// 6
// 5

Arrays

let nums = [42, 13, 78];
nums[0];  // 42
nums[2];  // 78
nums.length;  // 3

nums.push(99);
// now nums = [42, 13, 78, 99]

let last = nums.pop();
// now last = 99 and nums = [42, 13, 78]

let first = nums.shift();
// now first = 42 and nums = [13, 78]

nums.unshift(55);
// now nums = [55, 13, 78]


For more info, check the MDN Reference

Math Functions

let nearestInt = Math.round(1.55); 
// nearestInt is now 2

let nextLowestInt = Math.floor(1.55); 
// nextLowestInt is now 1

let nextHighestInt = Math.ceil(1.2); 
//nextHighestInt is now 2
      

Maps

//create a map
let englishToFrench = new Map(); 

//add new key/value pair
englishToFrench.set("hello", "bonjour");

// retrive a value via the key
let word = englishToFrench.get("hello");
// word is now set to "bonjour"

// check if a Map contains a key
englishToFrench.has("hello");
// would return true

// remove a key/value pair from the map
englishToFrench.delete("hello");

      
For more info, including using a forEach loop, 
check the MDN Reference
      

Strings

let name = "Navaneeth";

// determine length
console.log(name.length);  //9

// access a specific character in a string
let letter = name[2];
// letter is now set to "v"
// start counting index values from 0

// access a slice of a string
let part = name.substring(2, 5);
// part is now set to "van"
// from 2 go up to, but not including, 5

// build and concatenate a string
let someone = "Alastor";
someone += " Moody";
//someone is now set to "Alastor Moody"

    
For more info check the MDN Reference