JavaScript

UTF-16

Quotes

let single = 'single-quoted';
let double = "double-quoted";

let backticks = `backticks`;

${}

function sum(a, b) {
  return a + b;
}

alert(`1 + 2 = ${sum(1, 2)}.`); // 1 + 2 = 3.

let guestList = `Guests:
 * John
 * Pete
 * Mary
`;

alert(guestList); // 

let guestList = "Guests: // Error: Unexpected token ILLEGAL
  * John";

func`string` func docs tagged templates

newline character \n

let guestList = "Guests:\n * John\n * Pete\n * Mary";

alert(guestList); // 

let str1 = "Hello\nWorld"; // 

// 
let str2 = `Hello
World`;

alert(str1 == str2); // true

Unicode

alert( "\u00A9" ); // 
alert( "\u{20331}" ); //  Unicode
alert( "\u{1F60D}" ); //  Unicode

\

alert( 'I\'m the Walrus!' ); // I'm the Walrus!

\'

alert( `I'm the Walrus!` ); // I'm the Walrus!

\ JavaScript \ alert

\

\\

alert( `The backslash: \\` ); // The backslash: \

length

alert( `My\n`.length ); // 3

\n 3

pos [pos] str.charAt(pos)

let str = `Hello`;

// 
alert( str[0] ); // H
alert( str.charAt(0) ); // H

// 
alert( str[str.length - 1] ); // o

charAt

[] undefined charAt

let str = `Hello`;

alert( str[1000] ); // undefined
alert( str.charAt(1000) ); // ''

for..of

for (let char of "Hello") {
  alert(char); // H,e,l,l,ochar  "H" "e" "l" 
}

JavaScript

let str = 'Hi';

str[0] = 'h'; // error
alert( str[0] ); // 

str

let str = 'Hi';

str = 'h' + str[1];  // 

alert( str ); // hi

toLowerCase() toUpperCase()

alert( 'Interface'.toUpperCase() ); // INTERFACE
alert( 'Interface'.toLowerCase() ); // interface

alert( 'Interface'[0].toLowerCase() ); // 'i'

str.indexOf

str.indexOf(substr, pos)

pos str substr -1

let str = 'Widget with id';

alert( str.indexOf('Widget') ); // 0 'Widget' 
alert( str.indexOf('widget') ); // -1

alert( str.indexOf("id") ); // 1"id"  1 idget  id

"id" 1 2

let str = 'Widget with id';

alert( str.indexOf('id', 2) ) // 12

indexOf

let str = 'As sly as a fox, as strong as an ox';

let target = 'as'; // 

let pos = 0;
while (true) {
  let foundPos = str.indexOf(target, pos);
  if (foundPos == -1) break;

  alert( `Found at ${foundPos}` );
 pos = foundPos + 1; // 
}

let str = "As sly as a fox, as strong as an ox";
let target = "as";

let pos = -1;
while ((pos = str.indexOf(target, pos + 1)) != -1) {
  alert( pos );
}

if indexOf if

let str = "Widget with id";

if (str.indexOf("Widget")) {
    alert("We found it"); // 
}

alert str.indexOf("Widget") 0 if 0 false

-1

let str = "Widget with id";

if (str.indexOf("Widget") != -1) {
    alert("We found it"); // 
}

bitwiseNOT

bitwise NOT ~ 32-bit

32-bit ~n -(n+1)

alert( ~2 ); // -3 -(2+1) 
alert( ~1 ); // -2 -(1+1) 
alert( ~0 ); // -1 -(0+1) 
alert( ~-1 ); // 0 -(-1+1) 

n == -1 ~n 32-bit n

indexOf -1 if ( ~str.indexOf("...") )

indexOf

let str = "Widget";

if (~str.indexOf("Widget")) {
  alert( 'Found it!' ); // 
}

if (~str.indexOf(...)) if found

~ 32 0 ~4294967295=0

JavaScript .includes

includesstartsWithendsWith

str.includes(substr, pos) str substr true/false

alert( "Widget with id".includes("Widget") ); // true

alert( "Hello".includes("Bye") ); // false

str.includes

alert( "Widget".includes("id") ); // true
alert( "Widget".includes("id", 3) ); // false,  3  "id"

str.startsWith str.endsWith

alert( "Widget".startsWith("Wid") ); // true"Widget"  "Wid" 
alert( "Widget".endsWith("get") ); // true"Widget"  "get" 

JavaScript substringsubstr slice

str.slice(start [, end])

start end

let str = "stringify";
alert( str.slice(0, 5) ); // 'strin' 0  5  5
alert( str.slice(0, 1) ); // 's' 0  1 1 0 

slice

let str = "stringify";
alert( str.slice(2) ); // 

start/end

let str = "stringify";

// 
alert( str.slice(-4, -1) ); // 'gif'

str.substring(start [, end])

start end

slice start end

let str = "stringify";

//  substring 
alert( str.substring(2, 6) ); // "ring"
alert( str.substring(6, 2) ); // "ring"

//  slice 
alert( str.slice(2, 6) ); // "ring"
alert( str.slice(6, 2) ); // ""

slice 0

str.substr(start [, length])

start length

length

let str = "stringify";
alert( str.substr(2, 4) ); // 'ring' 2  4 

let str = "stringify";
alert( str.substr(-4, 2) ); // 'gi' 4  2 

1. alert( 'a' > 'Z' ); // true

2. alert( 'sterreich' > 'Zealand' ); // true

   Zealand sterreich

JavaScript

UTF-16

str.codePointAt(pos)

pos :

// 
alert( "z".codePointAt(0) ); // 122
alert( "Z".codePointAt(0) ); // 90

String.fromCodePoint(code)

code

alert( String.fromCodePoint(90) ); // Z

\u Unicode

//  90  5a
alert( '\u005a' ); // Z

65..220

let str = '';

for (let i = 65; i <= 220; i++) {
  str += String.fromCodePoint(i);
}
alert( str );
// ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~
// 

a > Z

a97 Z90

• a z

IE10- Intl.JS) ECMA-402

str.localeCompare(str2) str str2

• str str2
• str str2
• 0

alert( 'sterreich'.localeCompare('Zealand') ); // -1

"a" "a"

Unicode

2 2

2 65536 2

2

alert( ''.length ); // 2 X
alert( ''.length ); // 2
alert( ''.length ); // 2

JavaScript

length 2

String.fromCodePoint str.codePointAt String.fromCharCode str.charCodeAt fromCodePoint/codePointAt

alert( ''[0] ); // 
alert( ''[1] ); // 

alert

0xd800..0xdbff 0xdc00..0xdfff

// charCodeAt 

alert( ''.charCodeAt(0).toString(16) ); // d835 0xd800  0xdbff 
alert( ''.charCodeAt(1).toString(16) ); // dcb3,  0xdc00  0xdfff 

Iterable object

/

a UTF-16

UTF-16 Unicode

S dot above \u0307 S

alert( 'S\u0307' ); // S

dot below \u0323S S

alert( 'S\u0307\u0323' ); // S

Unicode

let s1 = 'S\u0307\u0323'; // SS +  + 
let s2 = 'S\u0323\u0307'; // SS +  + 

alert( `s1: ${s1}, s2: ${s2}` );

alert( s1 == s2 ); // false?!

Unicode

str.normalize()

alert( "S\u0307\u0323".normalize() == "S\u0323\u0307".normalize() ); // true

normalize() 3 \u1e68S

alert( "S\u0307\u0323".normalize().length ); // 1

alert( "S\u0307\u0323".normalize() == "\u1e68" ); // true

S UTF-16

Unicode Unicode

• 3 ${}
• JavaScript UTF-16
• \n \u... Unicode
• []
• slice substring
• /toLowerCase/toUpperCase
• indexOf includes/startsWith/endsWith
• localeCompare

• str.trim() (trims)
• str.repeat(n) n

/