From 218934fa2ed1c702a6d3923d2aa2cc6b43c48684 Mon Sep 17 00:00:00 2001 From: Peter Bengtsson Date: Tue, 8 Dec 2020 14:43:23 -0500 Subject: initial commit --- files/zh-tw/learn/javascript/howto/index.html | 294 ++++++++++++++++++++++++++ 1 file changed, 294 insertions(+) create mode 100644 files/zh-tw/learn/javascript/howto/index.html (limited to 'files/zh-tw/learn/javascript/howto') diff --git a/files/zh-tw/learn/javascript/howto/index.html b/files/zh-tw/learn/javascript/howto/index.html new file mode 100644 index 0000000000..5e5f7257c2 --- /dev/null +++ b/files/zh-tw/learn/javascript/howto/index.html @@ -0,0 +1,294 @@ +--- +title: JavaScript 解決常見的問題 +slug: Learn/JavaScript/Howto +translation_of: Learn/JavaScript/Howto +--- +
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+以下鏈接針對您需要修復的常見問題的解決方案，以便讓您的JavaScript語法正確執行。
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初學者常見的錯誤

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糾正語法和代碼

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如果您的代碼毫無反映或瀏覽器反饋某些內容「未定義」，請檢查您是否「正確輸入」所有變量名稱，函數名稱等。

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以下的常見造成問題的內置瀏覽器功能比對：

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正確 錯誤 
getElementsByTagName()getElementbyTagName()
getElementsByName()getElementByName()
getElementsByClassName()getElementByClassName()
getElementById()getElementsById()
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分號位置

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You need to make sure you don't place any semi-colons incorrectly. For example:

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CorrectWrong
elem.style.color = 'red';elem.style.color = 'red;'
+ +

功能內容

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There are a number of things that can go wrong with functions.

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One of the most common errors is to declare the function, but not call it anywhere. For example:

+ +
function myFunction() {
+  alert('This is my function.');
+};
+ +

This code won't do anything unless you call it, for example with

+ +
myFunction();
+ +

功能範圍

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Remember that functions have their own scope — you can't access a variable value set inside a function from outside the function, unless you declared the variable globally (i.e. not inside any functions), or return the value out of the function.

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在return語句後執行語法

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Remember also that when you return a value out of a function, the JavaScript interpreter exits the function — no code declared after the return statement will run.

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In fact, some browsers (like Firefox) will give you an error message in the developer console if you have code after a return statement. Firefox gives you "unreachable code after return statement".

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對象表示法與正確的指派

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When you assign something normally in JavaScript, you use a single equals sign, e.g.:

+ +
const myNumber = 0;
+ +

This doesn't work in Objects, however — with objects you need to separate member names from their values using colons, and separate each member with a comma, for example:

+ +
const myObject = {
+  name: 'Chris',
+  age: 38
+}
+ +

基本定義

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基本使用例子

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概括

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變量

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數學運算

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字串

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序列

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Debugging JavaScript

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For more information on JavaScript debugging, see Handling common JavaScript problems; also see Other common errors for a description of common errors.

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Making decisions in code

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Looping/iteration

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進階使用例子

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Functions

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對向

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JSON

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任務

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Object-oriented JavaScript

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網頁Web APIs

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