The implementation code of pre-input content is represented by asterisks in javascript.

For example, if it is 14 characters, 14 characters can be entered before the user input). When the user starts to input data, * is replaced in sequence, enter a few characters and replace them with a few characters. After the input, only the information entered by the user is displayed in the text box. I am still suffering from such a function for a while. Ah, the JS level is still too good, so I posted a post for help. Later, with the help of huangwenquan123, A CSDN user, I have fixed this problem. Now I am posting the Code directly, hoping to help my friends who need it:
Copy codeThe Code is as follows:
<Script type = "text/javascript" src = "http://demo.jb51.net/JSlib/jquery/jquery-1.3.2.min.js"> </script>
<Script type = "text/javascript">
$ (Document). ready (function (){
$ ("# TxtCustomsCode"). keydown (function (e) {// process the keydown event for the text box to be processed
E = e | window. event;
Var code = e. keyCode | e. which;
If (code> = 96 & code <= 105) | (code> = 65 & code <= 90) | (code> = 48 & code <= 57) {// you can enter uppercase/lowercase letters and numbers (including keypad)
Var userkeydown = $ (this). val (). substr (14 );
Var reg = /\*/;
$ (This). val ($ (this). val (). replace (reg, userkeydown ));
$ (This). val ($ (this). val (). substr (0, 14 ))
}
Else
$ (This). val ($ (this). val (). substr (0, 14 ))
})
})
</Script>