【正文】 上面例子中的變量 then實(shí)際上保存的是從計(jì)算機(jī)開始計(jì)數(shù)到在 2021年 1月 1日要經(jīng)過(guò)的毫秒數(shù)。 顯示最后更新的日期和時(shí)間的一個(gè)好的做法，因?yàn)轭l繁更新是網(wǎng)站質(zhì)量的標(biāo)志。 默認(rèn)情況下列表中只顯示有一項(xiàng)（用一條選擇語(yǔ)句），只 有用戶點(diǎn)擊下箭頭是才將列表其余部分展開。 該函數(shù)的基本結(jié)構(gòu)如下： function NameOfFunction( ) { JavaScript 代碼 } 事件處理程序 下面的例子展示了 onclick事件處理程序的使用，以及使用樣式來(lái)控制按鈕的外觀。 為了充分利用這些對(duì)話框的功能，則必須編寫更多的 JavaScript 代碼，來(lái)使用這些對(duì)話返回的參數(shù)值。 大連交通大學(xué) 2021 屆本科生畢業(yè)設(shè)計(jì)（論文）外文翻譯 4 /form /body /html Changing the code for the button to read onclick=myfunction( ) will result in exactly the same thing as the previous example if the following function is included in a script between the head tags. Typically, you would write a function only if the event required more than one thing to happen. function myfunction( ) { = } The following are some of the event handlers that exist in javascript: Table12 event handlers that exist in javascript onfocus onblur onselect onchange onsubmit onclick onmouseover onmouseout onload onunload onabort onerror onreset onkeypress onkeyup onmousedown onmousemove onmouseup onmove onresize POPUP MENUS PopUp Menus can be quickly created by using the select tag as it was used in forms to create a drop down list. Set the value of each of the options in the select tag to the url of the new page to be displayed. Use the onchange event handler to set the location of the window to the selected value in the drop down list. For example, if the form is named myform, the select tag is named mychoices, and the value of each option is a url then the sta tement = will take you to the new page that was selected from the drop down list. By default only one item in a list is displayed by a select statement until the viewer clicks on the down arrow to expose the rest of the list. To display more that one item at a time (and create a text box with a vertical scrollbar) include the size attribute in the select tag. For example, size=5 will display the first five items in the list and add a vertical scroll bar to the box if there are more than 5 items in the list. MOUSEOVERS A mouseover refers to the effect that occurs when the properties of an object are changed 大連交通大學(xué) 2021 屆本科生畢業(yè)設(shè)計(jì)（論文）外文翻譯 5 if the mouse is positioned over the top of the object and then again if the mouse is removed from the object. The quickest way to generate a mouseover is to use the onmouseover and onmouseout event handlers in a form of inline style. Visit the style section of the DHTML page of this web site to see an example of mouseovers used with text as an inline style. Any style property that applies to a particular object can be changed as the result of a mouseover. Performing mouseovers with a graphic is not much different than with text. When the desired event occurs (onmouseover, onmouseout) change the source of the graphic as in the example that follows: img src= onmouseover=src=39。39。 下面的語(yǔ)句會(huì)彈出一個(gè)對(duì)話框，需要回答是或否（確定或取消）。請(qǐng)注意，用簡(jiǎn)單的 type=button 來(lái)代替 type=submit。 要同時(shí)顯示一項(xiàng)以上內(nèi)容（建立一個(gè)有垂直滾動(dòng)條的文本框），在選擇標(biāo)簽中包含尺寸參數(shù)。 日期 /時(shí)間戳讓用戶知道信息的發(fā)布時(shí)間，因此表明了其有效性。 兩個(gè)數(shù)相減，并保存在一個(gè)新的變量里，將會(huì)得到當(dāng)前到目標(biāo)日期之間的毫秒數(shù)。 var now = new Date var then = new Date(January 1, 2021) 大連交通大學(xué) 2021 屆本科生畢業(yè)設(shè)計(jì)（論文）外文翻譯 14 上面例子中的變量 now 實(shí)際上保存的是從計(jì)算機(jī)開始計(jì)數(shù)到現(xiàn)在經(jīng)過(guò)的毫秒數(shù)。 var message = This is a test... var position = 0 function mymessage( ) { = (position, ) + (0, position) position = position + 1 if (position ) { position = 0 } (mymessage( ), 300) } 日期和時(shí)間 日期和時(shí)間，往往顯示在網(wǎng)頁(yè)顯示中，用于表明頁(yè)面的最后更新時(shí)間，加載時(shí)間，或顯示特定事的倒計(jì)時(shí)。 例如，如果窗體被命名為 myform，每個(gè)選項(xiàng)的值是一個(gè) URL，則語(yǔ)句 = 將帶你去一個(gè)下拉菜單中被選中的項(xiàng)。 當(dāng)被 HTML 文件的 BODY 中的一個(gè)事件處理程序調(diào)用時(shí)，函數(shù)將被執(zhí)行。 alert (將要顯示在警告框中的文本寫在引號(hào)之間 ) 此外，還有 其他類型的 預(yù)制對(duì)話框可用，如提示框和確認(rèn)框。 bordercolor : red} /style /head body form name=myform input type=button na