JavaScript var 语句

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</a></li> <li><a href="/ha/jsref/dom_obj_time.html" title="HTML DOM Time ɗanɗin"><time></a></li> <li><a href="/ha/jsref/dom_obj_title.html" title="HTML DOM Title ɗanɗin"><title></a></li> <li><a href="/ha/jsref/dom_obj_track.html" title="HTML DOM Track ɗanɗin"><track></a></li> <li><a href="/ha/jsref/dom_obj_u.html" title="HTML DOM Underline ɗanɗin"><u></a></li> <li><a href="/ha/jsref/dom_obj_ul.html" title="HTML DOM Ul ɗanɗin"><ul></a></li> <li><a href="/ha/jsref/dom_obj_var.html" title="HTML DOM Variable ɗanɗin"><var></a></li> <li><a href="/ha/jsref/dom_obj_video.html" title="HTML DOM Video ɗanɗin"><video></a></li> </ul> <h2>其他参考手册</h2> <ul> <li><a href="/ha/jsref/obj_cssstyledeclaration.html" title="CSSStyleDeclaration ɗanɗin">CSSStyleDeclaration</a></li> <li><a href="/ha/jsref/jsref_type_conversion.html" title="JavaScript ɗanɗin ɗanɗin">JS 类型转换</a></li> </ul> </div> <div><h3><center> 选修课 </center><h3> <h2>课程推荐：</h2> <ul> <li><a href="/ha/howto/index.html" title="CodeW3C.com ɗanɗin ɗanɗin">CodeW3C.com ɗanɗin ɗanɗin</a></li> </ul> </div> </div> <div id="maincontent"> <div class="idea"> <a href="/"><button>English</button></a> <a href="/zh/"><button>中文</button></a> <a href="/oldzh/"><button>繁體中文</button></a> <a href="/ru/"><button>Русский</button></a> <a href="/fr/"><button>Français</button></a> <a href="/de/"><button>Deutsch</button></a> <a href="/es/"><button>Español</button></a> <a href="/pt/"><button>Português</button></a> <a href="/ja/"><button>日本語</button></a> <a href="/ko/"><button>한국어</button></a> <a href="/it/"><button>Italiano</button></a> <a href="/ar/"><button>عربي</button></a> <a href="/hi/"><button>हिंदी</button></a> <a href="/bn/"><button>বাংলা</button></a> <a href="/ms/"><button>Bahasa Malaysia</button></a> <a href="/my/"><button>မြန်မာ</button></a> <a href="/vi/"><button>Tiếng Việt</button></a> <a href="/th/"><button>ภาษาไทย</button></a> <a href="/lo/"><button>ລາວ</button></a> <a href="/id/"><button>Bahasa Indonesia</button></a> <a href="/ur/"><button>اردو</button></a> <a href="/ha/"><button>Hausa</button></a> <a href="/pl/"><button>Język polski</button></a> <a href="/pa/"><button>ਪੰਜਾਬੀ</button></a> <a href="/sv/"><button>Svenska</button></a> <a href="/da/"><button>Dansk</button></a> <a href="/nl/"><button>Nederlands</button></a> <a href="/tr/"><button>Türkçe</button></a> <a href="/fi/"><button>suom.</button></a> <a href="/el/"><button>Ελληνικά</button></a> <a href="/fa/"><button>فارسی</button></a> <a href="/sw/"><button>Kiswahili</button></a> <a href="/te/"><button>తెలుగు</button></a> <a href="/tl/"><button>wikang Galu</button></a> </div> <h1>JavaScript var 语句</h1> <div class="prenextnav-ref"> <ul> <li> 上一页 <a href="/ha/jsref/jsref_try_catch.html" title="JavaScript try/catch/finally ɗanɗin">try...catch</a></li> <li> 下一页 <a href="/ha/jsref/jsref_while.html" title="JavaScript while ɗanɗin">while</a></li> <li> 返回上一层 <a href="/ha/jsref/jsref_statements.html" title="Nuna Nufin JavaScript Statement">Nuna Nufin JavaScript Statement</a></li> </ul> </div> <div> <h2>定义和用法</h2> <p>var 语句声明变量。</p> <p>变量是存储信息的容器。</p> <p>在 JavaScript 中创建变量称为“声明”变量：</p> <pre>var carName;</pre> <p>声明后，变量为空（没有值）。</p> <p>如需为变量赋值，请使用等号：</p> <pre>carName = "Volvo";</pre> <p>您还可以在声明变量时为其赋值：</p> <pre>var carName = "Volvo";</pre> <p>有关变量的更多知识，请学习我们的 JavaScript 变量教程和 JavaScript 作用域教程。</p> </div> <div> <h2>Diniki</h2> <p>创建一个名为 carName 的变量并为其赋值 "Volvo"：</p> <pre class="language-js"> var carName = "Volvo"; </pre> <p class="tiy"><a target="_blank" href="/ha/tiy/t.html?f=jsck_state_var_1">亲自试一试</a></p> <p>页面下方有更多 TIY 实例。</p> </div> <div> <h2>语法</h2> <pre>var <i>varname</i> = <i>value</i>;</pre> <h3>参数值</h3> <table class="dataintable"> <tr> <th style="width:22%;">参数</th> <th>描述</th> </tr> <tr> <td><i>varname</i></td> <td> <p>必需。指定变量的名称。</p> <p>变量名可以包含字母、数字、下划线和美元符号。</p> <ul> <li>变量名必须以字母开头</li> <li>变量名也可以以 $ 和 _ 开头</li> <li>变量名区分大小写（y 和 Y 是不同的变量）</li> <li>保留字（如 JavaScript 关键字）不能用作变量名</li> </ul> </td> </tr> <tr> <td><i>value</i></td> <td> <p>可选。指定要分配给变量的值。</p> <p class="note"><span>注释：</span>声明时未赋值的变量将拥有 undefined 值。</p> </td> </tr> </table> </div> <div> <h2>技术细节</h2> <table class="definition-usage"> <tr> <th style="width: 22%;">JavaScript 版本：</th> <td>ECMAScript 1</td> </tr> </table> </div> <div> <h2>更多实例</h2> <h3>Diniki</h3> <p>创建两个变量。将数字 5 赋给 x，将数字 6 赋给 y。然后显示 x + y 的结果：</p> <pre class="language-js"> var x = 5; var y = 6; document.getElementById("demo").innerHTML = x + y; </pre> <p class="tiy"><a target="_blank" href="/ha/tiy/t.html?f=jsck_state_var_2">亲自试一试</a></p> <h3>Diniki</h3> <p>Ayyuka dake aiki: An yi iya ayyuka dake aiki dake aiki.</p> <p>Ayyuka dake aiki: var dake aiki kuma kuma:</p> <pre class="language-js"> var lastName = "Gates", age = 19, job = "carpenter"; </pre> <p class="tiy"><a target="_blank" href="/ha/tiy/t.html?f=jsck_state_var_3">亲自试一试</a></p> <h3>Diniki</h3> <p>Ayyuka dake aiki:</p> <pre class="language-js"> var text = ""; var i; for (i = 0; i < 5; i++) { text += "Dabiya ce ni " + i + "<br>"; } </pre> <p class="tiy"><a target="_blank" href="/ha/tiy/t.html?f=jsck_state_for">亲自试一试</a></p> </div> <div> <h2>浏览器支持</h2> <table class="browser-support"> <tr> <th class="bsTh">语句</th> <th class="bsChrome">Chrome</th> <th class="bsIE">IE</th> <th class="bsFirefox">Firefox</th> <th class="bsSafari">Safari</th> <th class="bsOpera">Opera</th> </tr> <tr> <td>var</td> <td>支持</td> <td>支持</td> <td>支持</td> <td>支持</td> <td>支持</td> </tr> </table> </div> <div> <h2>相关页面</h2> <p>JavaScript 教程：<a href="/ha/js/js_variables.html" title="JavaScript ɗanɗin">JavaScript ɗanɗin</a></p> <p>JavaScript 教程：<a href="/ha/js/js_scope.html" title="JavaScript ɗanɗin">JavaScript ɗanɗin</a></p> </div> <div class="prenextnav-ref"> <ul> <li> 上一页 <a href="/ha/jsref/jsref_try_catch.html" title="JavaScript try/catch/finally ɗanɗin">try...catch</a></li> <li> 下一页 <a href="/ha/jsref/jsref_while.html" title="JavaScript while ɗanɗin">while</a></li> <li> 返回上一层 <a href="/ha/jsref/jsref_statements.html" title="Nuna Nufin JavaScript Statement">Nuna Nufin JavaScript Statement</a></li> </ul> </div><div style="background-color:#fcfdf8; 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