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// 1. 想要一个变量自己加1 num = num + 1 比较麻烦
var num = 1;
num = num + 1; // ++num
num = num + 1;
console.log(num); // 3
// 2. 前置递增运算符 ++ 写在变量的前面
var age = 10;
++age; // 类似于 age = age + 1
console.log(age);
// 3. 先加1 后返回值
var p = 10;
console.log(++p + 10);
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