JavaScript Learning Summary (22)--javascript shielded backspace key

Found today in IE browser, when using the readonly= "ReadOnly" property to set the text box to read-only <input type= "text" readonly= "readonly"/> There is a strange problem: if the cursor into a read-only text box, and then press the BACKSPACE key, it will jump to the previous page, the effect is like clicking the browser Back button back to the previous page, and in Firefox and Google no such problem appears, in order to solve this problem, Write a procedure like this, if the text box is read-only, then disable the BACKSPACE key.

The code is as follows:

1//Handling keyboard events prevents back key (Backspace) passwords or single-line, multiline text boxes except2functionBanbackspace (e) {3var ev = e | | window.event;//Get Event Object4var obj = Ev.target | | Ev.srcelement;//Get Event Source5var t = Obj.type | | Obj.getattribute (' type ');//Get Event Source Type6//Gets the event type as a criterion7var vreadonly = Obj.getattribute (' readonly ');8//Handling Null value Cases9 Vreadonly = (Vreadonly = = "")?False: vreadonly;10//When the BACKSPACE key is hit, the event source type is password or single line, multiline text,11//And the ReadOnly property is True or the Enabled property is False, the BACKSPACE key fails12var flag1= (Ev.keycode = = 8 && (t== "Password" | | t== "TEXT" | | t== "TEXTAREA")&& vreadonly== "ReadOnly")?TrueFalse;14//When the BACKSPACE key is hit, the event source type is non-password or single-line, multiline text, the BACKSPACE key is invalidated15var flag2= (Ev.keycode = = 8 && t! = "password" && t! = "text" && t! = "TEXTAREA")16?TrueFalse;1718//Judge19If(FLAG2) {20ReturnFalse;21st}22If(FLAG1) {23return false 24 } 25 }< Span style= "COLOR: #008080" >26 27 window.onload=function  () {28 // Disable back key action on Firefox, Opera29 document.onkeypress= banbackspace; 30 // No back key action on IE, chrome< Span style= "COLOR: #008080" >31 document.onkeydown=banbackspace;                 

With this processing, you can solve the "read-only input box under IE press the BACKSPACE key back to the previous page problem."

JavaScript Learning Summary (22)--javascript shielded backspace key