javascript - 无法调用未定义的方法 'split' - 从函数调用

Question

我有一个在加载时调用的 JS 函数，它会溢出一些变量，这一切都很好，但是当我从另一个函数调用该函数时，我得到这个错误 Cannot call method 'split' of undefined:

function loadInAttachmentsIntoSquads(){
    // eg: 5000,5000,5000,5000 > [5000][5000][5000]
    myAttachmentArray = currentAttachments.split(',');

    //eg: [5000][5000][5000] > [5][0][0][0]
    //myAttachmentForWeapon = myAttachmentArray[mySquadsIndex].split('');

    setupWeaponAttachments();
}


function setupWeaponAttachments(){

    myAttachmentForWeapon = myAttachmentArray[mySquadsIndex].split('');

    //if(mySquadsIndex == 0){
        if(myAttachmentForWeapon[1] == 1){ // if silencer is on? //first digit is always 5
            weaponAttachments.silencer = true;
        }
        else{
            weaponAttachments.silencer = false;
        }
        if(myAttachmentForWeapon[2] == 1){ // if silencer is on? //first digit is always 5
            weaponAttachments.grip = true;
        }
        else{
            weaponAttachments.grip = false;
        }
        if(myAttachmentForWeapon[3] == 1){ // if silencer is on? //first digit is always 5
            weaponAttachments.redDot = true;
        }
        else{
            weaponAttachments.redDot = false;
        }

    // -- applies visuals -- \\
    applyWeaponAttachments();
}

如果我从另一个函数调用 setupWeaponAttachments()，我会得到那个错误...为什么？

Answer 1

在以下内容中:

> function loadInAttachmentsIntoSquads(){
>     
>     myAttachmentArray = currentAttachments.split(',');
> 
>     setupWeaponAttachments(); 
> }

标识符 currentAttachments 被用作全局变量。如果在调用函数时还没有赋值，或者它的值不是字符串，那么就会产生错误。

所以解决方法是确保它有一个字符串值:

function loadInAttachmentsIntoSquads(){
    if (typeof currentAttachments != 'string') return;
    ...
}

或以其他方式处理错误。

此外，在执行所有这些 if..else block 的地方，请考虑:

weaponAttachments.silencer = myAttachmentForWeapon[1] == 1;
weaponAttachments.grip     = myAttachmentForWeapon[2] == 1;
weaponAttachments.redDot   = myAttachmentForWeapon[3] == 1;

它不会更快，但编写和读取的代码要少得多。