JavaScript 中 switch-case 语句中的变量声明
[英]Variable declaration in switch-case statements in JavaScript
问题描述
I have created a function day_of_week(dayy) and used switch-case statements in function.
我创建了一个函数 day_of_week(dayy) 并在函数中使用了 switch-case 语句。
function day_of_week(dayy) {
var result;
switch (dayy) {
case 1:
result = "monday";
case 2:
result = "Tuesday";
case 3:
result = "wednesday";
case 4:
result = "thursday";
case 5:
result = "friday";
case 6:
result = "saturday";
case 7:
result = "sunday";
default:
result = "No day";
}
document.write(result);
}
document.getElementById("switch").innerHTML = day_of_week(1);
document.getElementById("switch").innerHTML = day_of_week(2);
Actually in switch-case statements if there is no "break" the code should execute randomly.实际上在 switch-case 语句中，如果没有“中断”，代码应该随机执行。 But here when I declared variable called result and assigned the case values to it without "break".但是在这里，当我声明名为 result 的变量并在没有“中断”的情况下将 case 值分配给它时。 So, the code should execute all the cases randomly without any break.因此，代码应该随机执行所有案例而不会中断。 But, here the variable is under the instance of redeclaring the value and executing the last case.但是，这里的变量处于重新声明值并执行最后一种情况的实例下。 I am unable to know my mistake whether it is in declaring variable or using switch-case statements and all under the instance of function.我无法知道我的错误是在声明变量还是使用 switch-case 语句以及所有在函数实例下。 please help...请帮忙...
3 个解决方案
解决方案1
1 2020-09-08 17:11:05
There is no break statement in your code.您的代码中没有 break 语句。 I hope this will work for you.我希望这对你有用。
<!DOCTYPE html>
<html>
<head>
<script>
function day_of_week(dayy){
var result;
switch(dayy){
case 1: result = "Monday";
break;
case 2: result = "Tuesday";
break;
case 3: result = "wednesday";
break;
case 4: result = "Thursday";
break;
case 5: result = "Friday";
break;
case 6: result = "Saturday";
break;
case 7: result = "Sunday";
break;
default: result = "No day";
}
document.write(result);
}
document.getElementById("switch").innerHTML = day_of_week(2);
</script>
</head>
<body>
</body>
</html>
解决方案2
0 2020-09-08 17:09:19
I would do something like this to get a random day:我会做这样的事情来获得随机的一天：
function getDay() {
const days = ["monday", "tuesday", "wednesday", "thursday", "friday", "saturday", "sunday"];
return days[Math.floor(Math.random() * 7)];
}
解决方案3
0 2020-09-08 20:06:43
I refactor this code by using berak and Math method我使用 berak 和 Math 方法重构了这段代码
function day_of_week(day) {
var result;
switch (day) {
case 1:
result = "monday";
break;
case 2:
result = "Tuesday";
break;
case 3:
result = "wednesday";
break;
case 4:
result = "thursday";
break;
case 5:
result = "friday";
break;
case 6:
result = "saturday";
break;
case 7:
result = "sunday";
break;
default:
result = "No day";
}
document.write(result);
}
document.getElementById("switch").innerHTML = day_of_week(Math.floor( Math.random()*10));
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