This is a feature called destructuring assignment, which was added in JavaScript 1.7 and ECMAScript 6. It is not a part of ECMAScript 5: What is cross browser support for JavaScript 1.7’s new features? Specifically array comprehensions and the “let” statement
Destructure it by providing a valid key name like const { hello_en, ‘hello_zh-CN’: hello_zHCN, …rest } = data Working snippet var data = { hello_en: ‘hello world’, ‘hello_zh-CN’: ‘世界您好’, something: ‘nice day’, something_else: ‘isn\’t it’ } const { hello_en, ‘hello_zh-CN’: hello_zHCN, …rest } = data console.log(hello_zHCN);
It’s not necessarily true that a compiler/transpiler will always remove destructuring assignments as all evergreen browsers support destructuring natively as of 2020. As per, there is some evidence that as of at least 2018 the bytecode generated in V8 by a destructuring assignment is much more verbose than traditional function parameters: Function Parameters: function add(number1, … Read more
const data = { “key-with-dash”: [“BAZ”] } const {“key-with-dash”: foo} = data; console.log(“foo”, foo);
You can assign it a valid variable name using this syntax: var {“my name”: myName, age} = obj2; // use myName here
You cannot assign to this anywhere in the language. One option is to merge into this or other object: constructor(human) { Object.assign(this, human); }
Java Language Architect Brian Goetz has recently talked about adding destructuring to an upcoming version of Java. Look for the Sidebar: pattern matching chapter in his paper: Towards Better Serialization I strongly dislike the current proposal of the syntax, but according to Brian your use case will look like the following (please note, that at … Read more
Destructuring is just a nice way to unpack properties from objects and arrays and assign them to variables. As the trasnpiled code in the question suggests, any kind of operation is not possible. One hack would be to create 2 more variables (which don’t exist in input) and set the default value to the number … Read more
You can assign new variable names, like shown in this MDN Example var o = { p: 42, q: true }; // Assign new variable names var { p: foo, q: bar } = o; console.log(foo); // 42 console.log(bar); // true So, in your case, the code will be like this const b = 6; … Read more
There are multiple ways of doing this. The first one uses destructuring only and assigns the properties of options to properties on this: class Foo { constructor(options) { ({one: this.one, two: this.two} = options); // Do something else with the other options here } } The extra parentheses are needed, otherwise the JS engine might … Read more