在HTML5 / javascript中創建異常處理程序

Question

我是Web開發領域的新手，我想迷失在Java腳本函數中創建異常的步驟中

我想要做的是遵循以下語法的事情...

function exceptionhandler (){
     if (x===5)
     {
          //throw an exception
     }
}

我發現以下教程http://www.sitepoint.com/exceptional-exception-handling-in-javascript/但我不知道如何將上述if語句轉換為try..catch ... finally異常

謝謝！

Answer 1

要在JavaScript中 創建錯誤，您必須throw一些Error ，例如Error ， 特定類型的Error或任何Object或String 。

function five_is_bad(x) {
    if (x===5) {
        // `x` should never be 5! Throw an error!
        throw new RangeError('Input was 5!');
    }
    return x;
}

console.log('a');
try {
    console.log('b');
    five_is_bad(5); // error thrown in this function so this 
                    // line causes entry into catch
    console.log('c'); // this line doesn't execute if exception in `five_is_bad`
} catch (ex) {
    // this only happens if there was an exception in the `try`
    console.log('in catch with', ex, '[' + ex.message + ']');
} finally {
    // this happens either way
    console.log('d');
}
console.log('e');
/*
a
b
in catch with RangeError {} [Input was 5!]
d
e
*/

Answer 2

您可能正在尋找這樣的東西：

function exceptionhandler() {
    try {
        if (x===5) {
            // do something  
        }
    } catch(ex) {
        throw new Error("Boo! " + ex.message)
    }
}