
只能操作一个值的操作符叫做一元操作符, 例如递增和递减。
var num1 = 123;
num1++
num1++
num1--
++num1
--num1
num1 = ++num1 + num1
console.log(num1)
实验效果
var num1 = "abc";
var num2 = "cba";
console.log(typeof num1);
console.log(Boolean(num1));
var num3 = (!num1); //false
console.log(num3);
var num4 = (!num1 || num2);
console.log(num4);
var num4 = (num1 && num2);
console.log(num4);
实验效果
ECMAScript 定义了 3 个乘性操作符:乘法、除法和求模。
//乘性操作符
var num1 = 10;
var num2 = 20;
console.log("num1 * num2 = " + num1 * num2);
console.log("num2 / num2 = " + num2 / num1);
console.log("num1 % num2 = " + num1 % num2);
实验效果
加法和减法
//加性操作符
var num1 = 123;
var num2 = 234;
console.log(num1 + num2);
var str1 = "Hello";
var str2 = " World!";
console.log(str1 + str2);
var num3 = 123;
var num4 = 13;
console.log(num3 - num4);
var str3 = "Hello World!";
var str4 = "Hello";
console.log(str3 - str4);
实验效果
小于(<)、大于(>)、小于等于(<=)和大于等于(>=)
//比较运算符
var num1 = 10;
var num2 = 20;
console.log("num1 > num2 = " + (num1 > num2));
console.log("num1 < num2 = " + (num1 < num2 ));
console.log("num1 >= num2 = " + (num1 >= num2));
console.log("num1 <= num2 = " + (num1 <= num2));
实验代码
确定两个变量是否相等是编程中的一个非常重要的操作
//相等操作符
var num1 = 10;
var num2 = 10;
console.log("num1 == num2 = " + (num1 == num2));
console.log("num1 != num2 = " + (num1 != num2));
实验效果
条件操作符应该算是 ECMAScript 中最灵活的一种操作符
var max = (num1 > num2) ? num1 : num2;
如果 表达式成立,则值为: 前面的。 相反为:后面的。
//条件操作符
var num1 = 10;
var num2 = 20;
var nums = (num1 > num2) ? 30:40;
console.log(nums);
var nums = (num1 < num2) ? 30:40;
console.log(nums);
实验效果
简单的赋值操作符由等于号(=)表示,其作用就是把右侧的值赋给左侧的变量.
//赋值操作符
var num1 =10;
var num2 = 20;
//console.log("num2 = num1 = " + (num2 = num1));
//console.log("num2 += num1 = " + (num2 += num1));
//console.log("num2 *= num1 = " + (num2 *= num1));
console.log("num2 -= num1 = " + (num2 -= num1));
实验效果
使用逗号操作符可以在一条语句中执行多个操作
var a=1,b=2,c=3;
//逗号操作符
var num1=19,num2=20,num3=30;
console.log(num1,num2,num3);