| 12345678910111213141516171819202122232425262728293031323334 |
- <!DOCTYPE html>
- <html lang="en">
- <head>
- <meta charset="UTF-8">
- <title>Title</title>
- </head>
- <body>
- <form id="register" action="#" >
- <input type="text" onblur="onblurfunc" name="username" />
- <input type="submit" value="提交">
- </form>
- <script>
- const usernameInput = document.getElementsByName("username")[0]
- usernameInput.onblur = function(){
- if ( this.value.length < 6 ) {
- alert("长度不允许小于6位")
- this.value = ""
- }
- }
- function submit(){
- const username = usernameInput.value
- if ( username ) {
- return true
- }
- alert("用户名必须输入")
- return false
- }
- document.querySelector("#register").onsubmit = submit
- </script>
- </body>
- </html>
|
