W3SchoolHTML DOM Document getElementById() Method The getElementById() method returns an element with a specified value. The getElementById() method returns null if the element does not exist. The getElementById() 标记:Document Getelementbyid ValueGetelementbyid Innerhtml更多内容请查看https://www.w3schools.com/jsref/met_document_getelementbyid.asp
菜鸟教程https://www.runoob.com/jsref/met-document-getelementbyidHTML DOM getElementById() 方法 | 菜鸟教程网页getElementById() 方法可返回对拥有指定 ID 的第一个对象的引用。 HTML DOM 定义了多种查找元素的方法,除了 getElementById() 之外,还有 getElementsByName() 和 标记:JavascriptDocument Object Model更多内容请查看https://www.runoob.com/jsref/met-document-getelementbyid.html
菜鸟教程HTML DOM Input Text value 属性 | 菜鸟教程网页var at = document.getElementById("email").value.indexOf("@"); var age = document.getElementById("age").value; var fname = 更多内容请查看https://www.runoob.com/jsref/prop-text-value.html
W3SchoolHTML DOM Input Text value Property Syntax. Return the value property: textObject.value. Set the value property: textObject.value = text. Property Values. Technical Details. More Examples. Example. 更多内容请查看https://www.w3schools.com/jsref/prop_text_value.asp