05_beforestart.md

Things must know before go ahead

JS syntax is like C

if (score >= 60){
    console.log('passed!');
} else {
    console.log('failed!');
}

JS is Dynamic typing

Type checking is running at runtime

JS is Weak typing

Type can change on runtime

seven = '7';
eleven = 11;
console.log(seven + eleven);
// output '711'

variable eleven type auto convert from int to string

JS is Asynchronous

You can’t just call one function after another and hope they execute in the right order.

function first(){
  // Simulate a code delay
  setTimeout( function(){
    console.log(1);
  }, 500 );
}
function second(){
  console.log(2);
}
first();
second();
// output: 2
// output: 1

Hoisting

The variable and function declarations are put into memory during the compile phase, but stay exactly where you typed them in your code.

function catName(name) {
  console.log("My cat's name is " + name);
}

catName("Tigger");
// output: "My cat's name is Tigger"

Putting function declarations into memory before it executes any code segment is that it allows you to use a function before you declare it in your code.