快速创建数组,
new Array(10).fill('0').map( (item,index)=>{ console.log(index,item); return item; } )
动态属性，
const dynamic = 'flavour';
var item = { name: '前端小智', [dynamic]: '巧克力'}
console.log(item); // { name: '前端小智', flavour: '巧克力' }
空值合并??
const foo = null ?? 'Hello';console.log(foo); // 'Hello'
const bar = 'Not null' ?? 'Hello';console.log(bar); // 'Not null'
const baz = 0 ?? 'Hello';console.log(baz); // 0
//=======================
const a = 1;
const b = 2;
a &&= b;
console.log(a); // 2
// 上面等价于
a && (a = b);
// 或者
if (a) {a = b}
//=======================
const a = null;
const b = 3;
a ||= b;
console.log(a); // 3
// 上面等价于
a || (a = b);
//=======================
const a = null;
const b = 3;
a ??= b;
console.log(a); // 3
// 上面等价于
if (a === null || a === undefined) {
a = b;
}
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参考
https://segmentfault.com/a/1190000040704570