在函数 jQuery 之间传递的全局变量

Question

我正在设置一个变量...否则声明。但是，当我尝试在另一个函数中调用变量时，我收到未定义变量的错误。如何设置全局变量？

function username_check(){  
username = $('#username').val();
if(username == "" || username.length < 7 || username.indexOf(' ') > -1){
    usernameFilled = 0;
else{
    usernameFilled = 1;
}   
}
function email_check(){ 
email = $('#email').val();
if(email == "" || email.indexOf(' ') > -1) {
    emailFilled = 0;
}else{
    emailFilled = 1;
}
}
function password_length(){ 
password = $('#password').val();
if(password == "" || password.indexOf(' ') > -1) {
    passwordFilled = 0;
}else{
    passwordFilled = 1;
}
}
function password_check(){  
  password2 = $('#password2').val();
  password = $('#password').val();
  if(password2.length > 7 && password2 == password) {
    password2Filled = 1; /**setting the variable**/
  }else{
    password2Filled = 0;
  }
}
function upload(){
if (usernameFilled == 0 || emailFilled == 0 || passwordFilled == 0 || password2Filled == 0) {
    alert('All fields are required');
}else{
    /**upload to database**/
}

Answer 1

与其设置全局变量，不如返回 password2Fill 并将其保存在函数外部。然后，您可以将其传递给下一个函数。

即

function password_check(){  
   password2 = $('#password2').val();
   password = $('#password').val();
   if(password2.length > 7 && password2 == password) {
       password2Filled = 1; /**setting the variable**/
   }else{
       password2Filled = 0;
   }
   return password2Filled;
}
function upload(password2Filled)
{
    if (password2Filled == 0) { /**calling the variable**/
        alert('All fields are required');
    }else{
        /**upload to database**/
    }
}
....
var passwordsOk = password_check();
upload(passwordOk);

尽量避免全局变量，它们会使程序混乱，使难以看到代码流和创建可重用的代码。

Answer 2

您可能以错误的顺序调用函数，或者做错了其他事情，因为它对我来说很好用，稍微编辑了代码以对其进行测试：

function password_check(){  
  var password2 = $('#password2').val(), 
      password = $('#password').val();
  password2Filled = (password2.length > 7 && password2 == password) ? 1:0;
}
function upload(){
    console.log(password2Filled); //prints 0 or 1 just fine ???
}
$("#btn").on('click', function() {
    password_check();
    upload();
});

小提琴

Answer 3

您可以在 JavaScript 中创建全局变量，方法是在所有函数的范围之外定义它们。这样：

<script type="text/javascript">
var globalVariable;

function blah()
{
    globalVariable = "something";
}
function anotherFunction()
{
    alert(globalVariable);
}
</script>

ECMAScript/JavaScript 文档指出，"全局对象"应该在任何执行上下文之外创建。