thingsOfNote.html

<script>
let x = arr[i] || ' '; // <-- if arr[i] is falsy (doesnt return a value) x will be the string or the value after the ||

// run a for loop on two conditions being OR true, once one isnt true the other is checked for truth
	let indexZro = array[0];
	let indexOne = array[1];
	for (let i = 0; i < indexZro.length || i < indexOne.length; i++)

//use a object to change global variable localy without declaring locally
	let x = 0;

	foo();

	function foo(){
		myObj = {
			x: x // or just x <--- must remember though k name is inmutable
		}
	
		for (let i = 0; i < 10; i++){
			console.log(x);
			x++;
		
		} return x; // <---- fix 'undefined' // will return undifined if function doesnt 'return'
	}

//input into a string values or strings
	results += (X + ' ' + Y);

//input into an array values or strings
	arr.push(X + ' ' + Y); // you can add as much as you want into an index
	arr.push('\n'); //<---- this will be in its own index
	arr.push(X + ' ' + Y + '\n'); //<--- '\n' will be in same index as X and Y'

//logical operators
	1 == '1' //true
	1 === '1' //false
	a5 = 'Cat' && 'Dog' // returns dog
	a5 = 'Cat' || 'Dog' // returns cat
	bCon1 || (bCon2 && bCon3) //ither bCon1 is true/false OR (bCon2 AND bcon3) is true/false
	
	
//Callback Functions-  to be used when one function needs to 
//wait for the completion of another

		let family = ['wife','son','sister'];
		
		function fooOne(family, callback){
			// do something that takes 1 minute
			callback();
		}
		
		function fooTwo() {
			//do something that only takes 30 seconds
			// this is 'called back' after completion of 'fooOne'
		}
		
	fooOne(family, fooTwo);

// Test for undefined
	if (x === undefined) {
		// these statements execute
	}

//Execute for each index in an array
	let array = ['index_0','index_1'];
	
	array.forEach(foo); // foo = built function

//deep dig into objects key and properties
	var myObj = {
		locations: {
			cities: ['Boston', 'New York', 'Baltimore', 'Miami']
		}
	}

	console.log(myObj.locations.cities[2]); //=> baltimore
	console.log(myObj['locations']['cities'][0]); //boston
  </script>