JavaScript | Tech控え帳

1-1. var

関数スコープ
厳密には、function, module, namespace, or global scope

function scope_sample_var() {
    var i = 1;
    console.log(i);         // => 1
    {
        var i = 2;
        console.log(i);     // => 2
    }
    console.log(i);         // => 2
}

scope_sample_var();

function scope_sample_var() {

var i = 1;

console.log(i); // => 1

{

var i = 2;

console.log(i); // => 2

}

console.log(i); // => 2

}

scope_sample_var();

JavaScript (ECMAScript 6) の分割代入 (Destructuring assignment)

簡単な例

const obj = {name:'Jane', age:18};

const {name:s, age:i} = obj;
// s = 'Jane' ; i = 18

const {name, age} = obj;
// name = 'Jane' ; age = 18

const obj = {name:'Jane', age:18};

const {name:s, age:i} = obj;

// s = 'Jane' ; i = 18

const {name, age} = obj;

// name = 'Jane' ; age = 18

応用例

const {dialog} = require('electron').remote;

1	const {dialog} = require('electron').remote;

以下のコードと等価

const remote = require('electron').remote;
const dialog = remote.dialog;

1 2	const remote = require('electron').remote; const dialog = remote.dialog;

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「JavaScript」タグアーカイブ

var と let の違い

1. ECMAScript 2015 / ECMAScript 6 (ES6), [TypeScript]

1-1. var

分割代入 (Destructuring assignment)

簡単な例

応用例