js 运算符的执行顺序
js 运算符优先级
Operator Precedence
下表从最高（21）到最低（1）优先顺序排列
left-to-right
从左到右 / 先左后右
right-to-left
从右到左 / 先右后左
逻辑非
一元加减
一元加 / 一元减
Precedence & Associativity
优先级 & 关联性
let a, b;
a = b = 5;
// same as writing
a = (b = 5);
a || (b * c); // evaluate `a` first, then produce `a` if `a` is "truthy"
a && (b < c); // evaluate `a` first, then produce `a` if `a` is "falsy"
a ?? (b || c); // evaluate `a` first, then produce `a` if `a` is not `null` and not `undefined`
a?.b.c; // evaluate `a` first, then produce `undefined` if `a` is `null` or `undefined`
demo
"use strict";
/**
*
* @author xgqfrms
* @license MIT
* @copyright xgqfrms
* @created 2020-10-01
* @modified
*
* @description
* @difficulty Easy Medium Hard
* @complexity O(n)
* @augments
* @example
* @link
* @solutions
*
* @best_solutions
*
*/
const log = console.log;
// console.log(([][[]]+[])[+!![]]+([]+{})[!+[]+!![]]);
// log(([][[]]+[])[+!![]]+([]+{})[!+[]+!![]]);
log([]);
log([[]]);
log(+[]);
log([][[]]);
log(([][[]]+[]));
log([+!![]]);
log(!![]);
log(+!![]);
log(`
+true =`, +true)
// log(([][[]]+[])[]);
// log((undefined)[0])
// log((undefined)[1])
log(+([]+{}));
log([]+{});
log(+[]);
// 0
log(!+[]);
// true
log(`
!0 =`, !0);
// true
log(!![]);
// true
log(+!![]);
// 1
log(`
+true =`, +true);
// 1
log(!+[]+!![]);
// 2
log(`
true + true =`, true + true);
// 2
log([!+[]+!![]]);
// [2]
log(``, +([]+{})[!+[]+!![]])
// NaN
log(``, ([]+{})[!+[]+!![]])
// "b"
refs
https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Operators/Operator_Precedence
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