Viewing: ko.javascript.info

. .

( ).

[]

, .

. , .

(Egyptian) . . .

          if (condition) {
  //  1
  //  2
  // ... n...
}
        

if (condition) doSomething() . ?

, .

if (n < 0) {alert(`Power ${n} is not supported`);}

, . .

          if (n < 0)
  alert(`Power ${n} is not supported`);
        

if (n < 0) alert(`Power ${n} is not supported`);

          if (n < 0) {
  alert(`Power ${n} is not supported`);
}
        

if (cond) return null . .

. .

          // (`)        .
let str = `
  ECMA International's TC39 is a group of JavaScript developers,
  implementers, academics, and more, collaborating with the community
  to maintain and evolve the definition of JavaScript.
`;
        

if .

          if (
  id === 123 &&
  moonPhase === 'Waning Gibbous' &&
  zodiacSign === 'Libra'
) {
  letTheSorceryBegin();
}
        

. 80 120 .

(Tab) . , .

          show(parameters,
     aligned, //      
     one,
     after,
     another
  ) {
  // ...
}
        

. , , .

          function pow(x, n) {
  let result = 1;
  //              <--
  for (let i = 0; i < n; i++) {
    result *= x;
  }
  //              <--
  return result;
}
        

. .

. . .

StandardJS . .

continue .

if .

          for (let i = 0; i < 10; i++) {
  if (cond) {
    ... // <-     .
  }
}
        

continue .

          for (let i = 0; i < 10; i++) {
  if (!cond) continue;
  ...  // <-     .
}
        

if/else return .

          function pow(x, n) {
  if (n < 0) {
    alert("'n'    .");
  } else {
    let result = 1;

    for (let i = 0; i < n; i++) {
      result *= x;
    }

    return result;
  }
}
        

          function pow(x, n) {
  if (n < 0) {
    alert("'n'    .");
    return;
  }

  let result = 1;

  for (let i = 0; i < n; i++) {
    result *= x;
  }

  return result;
}
        

n < 0 ' , return . .

          //  
function createElement() {
  ...
}

function setHandler(elem) {
  ...
}

function walkAround() {
  ...
}

//    
let elem = createElement();
setHandler(elem);
walkAround();
        

          //    
let elem = createElement();
setHandler(elem);
walkAround();

// ---   ---
function createElement() {
  ...
}

function setHandler(elem) {
  ...
}

function walkAround() {
  ...
}
        

' . .

' , , , .

, .

. , .

Linter

Linter , .

, . ' linter linter .

linter:

JSLint linter
JSHint JSLint linter
ESLint linter

linter . ESLint .

linter . .

ESLint linter .

Node.js .
npm( ) ESLint . npm install -g eslint
( ) .eslintrc .
ESLint . ESLint .

.eslintrc .

          {
  "extends": "eslint:recommended",
  "env": {
    "browser": true,
    "node": true,
    "es6": true
  },
  "rules": {
    "no-console": 0,
    "indent": ["warning", 2]
  }
}
        

"extends" "eslint:recommended" . .

. http://eslint.org/docs/user-guide/getting-started .

IDE lint ESLint .

" ?" " ?" . .

          function pow(x,n)
{
  let result=1;
  for(let i=0;i<n;i++) {result*=x;}
  return result;
}

let x=prompt("x?",''), n=prompt("n?",'')
if (n<=0)
{
  alert(`Power ${n} is not supported, please enter an integer number greater than zero`);
}
else
{
  alert(pow(x,n))
}
        

          function pow(x,n)  // <-    
{  // <-    
  let result=1;   // <-   = /  
  for(let i=0;i<n;i++) {result*=x;}   //   < /  
  // { ... }     
  return result;
}

let x=prompt("x?",''), n=prompt("n?",'') // <--    ,
//      ,  /    ;   
if (n<=0)  // <- (n <= 0)     ,   ( )
{   // <-    
  //            
  alert(`Power ${n} is not supported, please enter an integer number greater than zero`);
}
else // <- "} else {" else      
{
  alert(pow(x,n))  //  ;  
}
        

          function pow(x, n) {
  let result = 1;

  for (let i = 0; i < n; i++) {
    result *= x;
  }

  return result;
}

let x = prompt("x?", "");
let n = prompt("n?", "");

if (n <= 0) {
  alert(`Power ${n} is not supported,
    please enter an integer number greater than zero`);
} else {
  alert( pow(x, n) );
}
        