'use strict';

// comment

/* still

comment */

var x1 = 233;

console.log(x1);

if (2>1) {x1 = 322;}

typeof(233);

// number

233;

2.33;

2.33e3;

-233;

NaN;

Infinity;

0xe9; //233

(1 + 2) * 5 / 2; //7.5

2 / 0; //Infinity

0 / 0; // NaN

10 % 3; //1

10.5 % 3; //1.5

// string

'abc';

"abc";

'\'';

"\"";

"\n\t\n\r\\";

'\x41'; //ASCII 'A'

'\u0041'; //utf-8 'A'

`233

233

233`; //backquote

'hello, ' + 233;

var x1 = 233;

`hello, ${x1}`;

'233'.length;

'233'[0];

'abc'.toUpperCase().toLowerCase();

'abc'.indexOf('bc')

'abc'.substring(0, 3)

// bool

true;

false;

2>1;

2===2; //never use "==" although js supports

2<1;

true && false;

true || false;

!true;

!false;

if (true) { alert('if1') }

if (false) { alert('never run'); } else { alert('if2'); }

NaN === NaN; //false

isNaN(NaN);

Math.abs(1-0.999)<0.1;

Boolean(null);

Boolean(undefined);

Boolean(0);

Boolean('');

Boolean(false);

//special

null;

undefined;

//array

[233,2.33,NaN,Infinity,'233',true,false,null,undefined,[]]

new Array(2,3,3);

[2,3,3][1]; //indexing start with 0

var x1 = [2,3,3];

x1.length;

x1[6] = 233;

x1.length;

for (var y of x1) { console.log(y); }

x1.forEach(function (element, index, array) { console.log(element.toString() + '::' + index.toString());});

//dict

var x1 = {

name: '233',

age: 233

};

x1.name;

x1['name'];

x1.name = '322';

delete x1.age;

'name' in x1;

'toString' in x1;

x1.hasOwnProperty('name');

x1.hasOwnProperty('toString');

//for-loop, while-loop, do-while-loop

var x1 = 0;

var i;

for (i=1; i<=100; i++){

x1 = x1 + i;

}

//Map

var x1 = new Map([['Michael',95],['Bob',75],['Tracy',85]]);

// var x1 = new Map();

x1.get('Bob');

x1.set('Adam', 67);

x1.has('Adam');

x1.delete('Adam');

for (var y of x1){

console.log(y[0]);

console.log(y[1]);

}

//Set

var x1 = new Set([2,3,3]);

x1.add('2');

x1.delete('2');

for (var y of x1){ console.log(y); }

x1.forEach( function(y){ console.log(y);} );