位运算
取整
console.log(~~(11.11));
console.log(11.11 >> 0);
console.log(11.11 << 0);
console.log(11.11 | 0);
console.log(11.11 >>> 0);
判断奇偶
console.log(7 & 1);
console.log(8 & 1);
转换布尔值
console.log(!!7);
console.log(!!0);
console.log(!!-1);
console.log(!!0.71);
console.log(!!"");
console.log(!![]);
console.log(!!{}"); // true
console.log(!!null); // false
console.log(!!undefined); // false
移位运算
console.log(16 >> 1);
console.log(16 >> 2);
console.log(1 >>> 1);
进行值交换
let a = 7;
let b = 1;
a ^= b;
b ^= a;
a ^= b;
console.log(a);
console.log(b);
b = [a, a = b][0];
[a, b] = [b, a];
判断符号是否相同
let a = 1;
let b = 1;
console.log((a ^ b) >= 0);
console.log((a ^ -b) >= 0);
检查数字是否不相等
let a = 111;
if (a ^ 111) console.log("Not equal");
if (a !== 111) consoel.log("Not equal");
if (a ^ 11111) console.log("Not equal");
判断是否2的整数幂
const check = n => !(n & (n - 1));
console.log(check(7));
console.log(check(8));
条件语句
let bool = true;
if (bool) console.log(1);
console.log(bool && console.log(1));
四舍五入取整
const round = n => n + 0.5 * (n > 0 ? 1: -1) | 0;
console.log(round(0));
console.log(round(1.1));
console.log(round(1.6));
console.log(round(-1.1));
console.log(round(-1.6));
字符串
取随机字符串
console.log(Math.random().toString(16).slice(2));
重复字符串
const repeat = (n, str) => Array(n+1).join(str);
console.log(repeat(5, "ab"));
console.log("ab".repeat(5));
创建链接
console.log("Google".link("www.google.com"));
其他
正确处理异常的方法
try {
} catch (e) {
window.location.href = "http://stachoverflow.com/search?q=[js]+" + e.message;
}
可以替代undefined的操作
console.log(void 0);
console.log(""._);
console.log(1.._);
console.log(0[0]);
替代Infinity
console.log([-1/0, 1/0]);
清空数组
let isIE8 = !+"1";
console.log(isIE8);
快速判断IE8以下的浏览器
let isIE8 = ! + "1";
console.log(isIE8);