SWITCH javascript 总是执行默认情况的问题 [英] trouble with SWITCH javascript always executing default case

问题描述

嗯，我有这个问题，我一直在处理，但我无法让它工作

well i have this trouble and ive been dealing with but i just cant get it to work

我有这个功能

function getDirections(dir)
{
var img;
switch(dir)
    {
    case 0:
    img+='N.png';
    break;  
    case 1:
    img+='NE.png';
    break;
    case 2:
    img+='E.png';
    break;
    case 3:
    img+='SE.png';
    break;
    case 4:
    img+='S.png';
    break;
    case 5:
    img+='SO.png';
    break;
    case 6: 
    img+='O.png';
    break;
    case 7:
    img+='NO.png';
    break;
    default:
    alert('enetered default but direction='+dir);
    }
return img;
}

很简单吧?现在我将此间隔设置为 5000 毫秒来调用 getDirections(variable)，该函数在第一次调用时运行良好，但在此之后，它总是进入 default 子句，并且还提醒已输入默认值但方向 = dirvalue"，我的意思是，即使 dir 是 0-7 之间的值，它也将始终进入默认值:但它会提醒该值，因此它应该进入其中一种情况.

quite simple right? now i have this interval set to 5000 ms to call getDirections(variable), the function works well the first time its called but after that , it always enter in the default clause and it also alerts the 'entered default but direction=dirvalue' , i mean even if dir is a value between 0-7 it will always enter to default: but it would alert the value so it was supossed to enter to one of the cases.

我用 else if 做了同样的事情，它起作用了，所以我不知道 SWITCH 有什么问题

i made the same using else if and it worked so i dont know what its wrong with SWITCH

if(dir==0){img+='N.png';}
else if(dir==1){img+='NE.png';}
else if(dir==2){img+='E.png';}
else if(dir==3){img+='SE.png';}
else if(dir==4){img+='S.png';}
else if(dir==5){img+='SO.png';}
else if(dir==6){img+='O.png';}
else if(dir==7){img+='NO.png';}

推荐答案

这很奇怪...尝试确保 dir 是 int，在切换之前执行此操作:

That is weird... try to make sure that dir is an int, do this before the switch:

dir = parseInt(dir);

如果警报正确显示值，它应该进入开关，但它仍然可以看起来"正确但具有不同的数据类型.手动进行转换以确保它是一个 int

If the alert shows the value correctly it should enter the switch, but still it can "look" correct but be of a different data type. Do the conversion manually to ensure it's an int

这篇关于SWITCH javascript 总是执行默认情况的问题的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！