blob: 0b44186a971155f6df9af7b7284afb2445326168 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
|
---
title: Number 和 String 函數
slug: >-
Web/JavaScript/Obsolete_Pages/Obsolete_Pages/Obsolete_Pages/預先定義的函數/Number_和_String_函數
translation_of: Web/JavaScript/Guide/Functions
translation_of_original: >-
Web/JavaScript/Guide/Obsolete_Pages/Predefined_Functions/parseInt_and_parseFloat_Functions
---
<h4 id="Number_和_String_函數">Number 和 String 函數</h4>
<div class="onlyinclude">
<p><code>Number</code> 和 <code>String</code> 函數讓你把物件轉換為數字或字串。這些函數的語句是︰</p>
<pre>var objRef=Number(objRef);
var objRef=String(objRef);
</pre>
<p>此處的 <code>objRef</code> 就是物件的參考。</p>
<p>以下的範例把 <code><a class="internal" href="/zh_tw/Core_JavaScript_1.5_%E5%8F%83%E8%80%83/%E5%85%A8%E5%9F%9F%E7%89%A9%E4%BB%B6/Date" title="zh tw/Core JavaScript 1.5 參考/全域物件/Date">Date</a></code> 物件轉換為可讀的字串。</p>
<pre>var D = new Date (430054663215);
// 返回以下字串
// "Thu Aug 18 04:37:43 GMT-0700 (Pacific Daylight Time) 1983"
var x = String(D);
</pre>
</div>
<p> </p>
<p>以下範例把 <code><a class="internal" href="/zh_tw/Core_JavaScript_1.5_%E5%8F%83%E8%80%83/%E5%85%A8%E5%9F%9F%E7%89%A9%E4%BB%B6/String" title="zh tw/Core JavaScript 1.5 參考/全域物件/String">String</a></code> 物件轉換為 <a class="internal" href="/zh_tw/Core_JavaScript_1.5_%E5%8F%83%E8%80%83/%E5%85%A8%E5%9F%9F%E7%89%A9%E4%BB%B6/Number" title="zh tw/Core JavaScript 1.5 參考/全域物件/Number"><font face="Courier New">Number</font></a> 物件。</p>
<pre>var str="12";
var num=Number(str);
</pre>
<p>你可以使用 DOM 的方法 write() 和 JavaScript 的 typeof 運算子來檢驗。</p>
<pre>var str="12";
document.write(typeof str);
document.write("<br/>");
var num=Number(str);
document.write(typeof num);
</pre>
<p> {{ PreviousNext("Core_JavaScript_1.5_教學:預先定義的函數:parseInt_和_parseFloat_函數", "Core_JavaScript_1.5_教學:預先定義的函數:escape_和_unescape_函數") }}</p>
<p>{{ languages( {"en": "en/Core_JavaScript_1.5_Guide/Predefined_Functions/Number_and_String_Functions", "es": "es/Gu\u00eda_JavaScript_1.5/Funciones_predefinidas/Funciones_Number_y_String", "fr": "fr/Guide_JavaScript_1.5/Fonctions_pr\u00e9d\u00e9finies/Les_fonctions_Number_et_String", "ja": "ja/Core_JavaScript_1.5_Guide/Predefined_Functions/Number_and_String_Functions", "pl": "pl/Przewodnik_po_j\u0119zyku_JavaScript_1.5/Funkcje_predefiniowane/Funkcje_Number_i_String" } ) }}</p>
|
