//写法一:
if (condition) {
code to run if condition is true
} else {
run some other code instead
}
//写法二:
if (condition) {
code to run if condition is true
}
run some other code
//写法三:
if (condition) code to run if condition is true
else run some other code instead
1.2 嵌套if … else
if (condition) {
code to run if condition is true
} else if(condition) {
code to run if condition is true
} else {
run some other code instead
}
2. switch语句
switch (expression) {
case choice1:
run this code
break;
case choice2:
run this code instead
break;
// include as many cases as you like
default:
actually, just run this code
}
//default 部分不是必须的,通过它来处理未知的情况。
3. 三元运算符
( condition ) ? run this code : run this code instead
( select.value === 'black' ) ? update('black','white') : update('white','black');
//它以测试条件开始select.value === 'black'。如果返回true,运行update()带有黑色和白色参数的函数.
//如果返回false,我们运行update()带有白色和黑色参数的函数。