使用 javascript 或 Jquery 或正则表达式验证器限制文本框中的小于 < 和大于 > 字符

Question

<asp:TextBox ID="txt" runat="server" MaxLength="95" Width="95%" Height="20px"  onKeypress="CheckExpression(event,this.id)"></asp:TextBox>

And function code is:-

function CheckExpression(evtobj, id) {

    if (evtobj.keyCode === 60 || evtobj.keyCode === 62) {
        alert();
        evtobj.preventDefault();
    }
}

Answer 1

You may try the following approach, it will prevent inserting > and < sign.

 function myKeyPress(e){ var keynum; if(window.event) { // IE keynum = e.keyCode; } else if(e.which){ // Netscape/Firefox/Opera keynum = e.which; } if(keynum==62 || keynum==60) e.preventDefault(); }

 <input id="txt" onkeypress="return myKeyPress(event)" />

Answer 2

It's quite late but following solution will work for you.

<textarea name="comments" id="comments" rows="3" 
maxlength="250"placeholder="Enter message or question here"></textarea>

// Restrict user to enter less than and greater than (<>) symbol using javascript.

let commentBox = document.getElementById('comments');


commentBox.addEventListener("keypress", e => {
      let charCode = (e.which) ? e.which : e.keyCode;
      console.log(charCode); // You can see the code of character 
      if (charCode == 60 || charCode == 62) {
            //prevent default behaviour
            e.preventDefault();
            return false;  
        } 
    });

// Restrict copy & paste in text area.  
commentBox.addEventListener("paste", e => {
    e.preventDefault();
    return false;  
});