JavaScript Basics, Login verification

Source: Internet
Author: User
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Three ways to use <script></script>:

  1. Put in the <body>
  2. Put in the
  3. Placed in an external JS file
    <! DOCTYPE html>"en">"UTF-8"> <title> my </title> <script>function Displaydate () {document.getElementById ("Demo"). innerhtml=Date (); }    </script> <script src="24.js"></script>"Demo">ppp</p> <script>document.write (Date ()); document.getElementById ("Demo"). innerhtml=Date (); </script><buttom type="Button"Onclick=window.alert (" Number") >press</buttom></body>Copy Code function myFunction () {Document.getelementbyld ("Demo"). innerhtml="my first JavaScript function";}

    Three ways to output data:

    1. Use the document.write () method to write content to an HTML document.
    2. Use the Window.alert () pop-up warning box.
    3. Writes to an HTML element using InnerHTML.
      1. Use the ID property to identify the HTML element.
      2. Use the document.getElementById (ID) method to access HTML elements.
      3. Use innerHTML to get or insert element content.
        Copy Code<! DOCTYPE html>"en">"UTF-8"> <title> my </title>"Demo">ppp</p> <script>//document.write (Date ());document.getElementById ("Demo"). innerhtml=Date (); </script><buttom type="Button"Onclick=window.alert (" Number") >press</buttom></body>Copy Code

            1. The login page prepares:
              1. Add an Error prompt box.
              2. Write a good html+css file.
              3. Set the ID of each INPUT element
            2. Defines a JavaScript function.
              1. Verify user name 6-20-bit
              2. Verify password 6-20-bit
            3. The onclick invokes this function.
        <! DOCTYPE html>"en">"UTF-8"> <title> Login </title> <script>function Fnlogin () {varOuname=document.getelementbyid ("uname")            varOerror=document.getelementbyid ("Error_box")            if(ouname.value.length<6) {oerror.innerhtml="user name at least 6 bits"            }            if(ouname.value.length>6&opassward.value.length<6) {oerror.innerhtml="password is at least 6 bits"            }        }    </script>class="Box"> class="Input_box"> <input id="uname"Type="text"Placeholder="Please enter user name"> </div> <divclass="Input_box"> <input id="UPass"Type="Password"Placeholder="Please enter your password"> </div> <div id="Error_box"><br></div> <divclass="Input_box"> <button onclick="Fnlogin ()"> Login </button> <button type="Button"Onclick=window.alert ("account password is empty, please enter! ") > not entered the account password </button> </div></div></body>

JavaScript Basics, Login verification

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