diff options
Diffstat (limited to 'files/zh-tw/web/javascript/reference/global_objects/undefined/index.html')
| -rw-r--r-- | files/zh-tw/web/javascript/reference/global_objects/undefined/index.html | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/files/zh-tw/web/javascript/reference/global_objects/undefined/index.html b/files/zh-tw/web/javascript/reference/global_objects/undefined/index.html index f352c84d71..f183c412ce 100644 --- a/files/zh-tw/web/javascript/reference/global_objects/undefined/index.html +++ b/files/zh-tw/web/javascript/reference/global_objects/undefined/index.html @@ -26,8 +26,8 @@ translation_of: Web/JavaScript/Reference/Global_Objects/undefined <p>A variable that has not been assigned a value is of type undefined. A method or statement also returns <code>undefined</code> if the variable that is being evaluated does not have an assigned value. A function returns <code>undefined</code> if a value was not {{jsxref("Statements/return", "returned")}}.</p> -<div class="warning"> -<p>While it is possible to use it as an {{Glossary("Identifier", "identifier")}} (variable name) in any scope other than the global scope (because <code>undefined</code> is not a {{jsxref("Reserved_Words", "reserved word")}}), doing so is a very bad idea that will make your code difficult to maintain and debug.</p> +<div class="notecard warning"> +<p><strong>Warning:</strong> While it is possible to use it as an {{Glossary("Identifier", "identifier")}} (variable name) in any scope other than the global scope (because <code>undefined</code> is not a {{jsxref("Reserved_Words", "reserved word")}}), doing so is a very bad idea that will make your code difficult to maintain and debug.</p> <pre class="brush: js">//DON'T DO THIS @@ -54,8 +54,8 @@ else { } </pre> -<div class="note"> -<p>備註：The strict equality operator rather than the standard equality operator must be used here, because <code>x == undefined</code> also checks whether <code>x</code> is <code>null</code>, while strict equality doesn't. <code>null</code> is not equivalent to <code>undefined</code>. See {{jsxref("Operators/Comparison_Operators", "comparison operators")}} for details.</p> +<div class="notecard note"> +<p><strong>Note:</strong> The strict equality operator rather than the standard equality operator must be used here, because <code>x == undefined</code> also checks whether <code>x</code> is <code>null</code>, while strict equality doesn't. <code>null</code> is not equivalent to <code>undefined</code>. See {{jsxref("Operators/Comparison_Operators", "comparison operators")}} for details.</p> </div> <h3 id="Typeof_operator_and_undefined"><code>Typeof</code> operator and <code>undefined</code></h3> |