Validate with regex that the string contains only numbers and a negative sign at the beginning

Question

Validate with regex that the string contains only numbers and a negative sign at the beginning

Hello, I am attempting to create a regular expression for an input field that will only accept 4 numbers less than or equal to 2934, but will also allow for a negative number like -2394.

My goal is to permit the minus sign only at the beginning of the string, followed by exactly 4 numbers, not exceeding 2934 (both positive and negative, as they represent coordinates).

I have already tried the solutions provided here, but it seems like there is something missing.

function numonly(myfield, e, dec){
      // maximum input value of 4196 x 4196
      $("#mlat,#mlon").keyup(function() {
        var val = $(this).val().replace(/[^0-9]+/,"");
        if (val >= 2934){
          !/^\s*$/.test(val);
          val = (parseInt(val) > 2934) ? 2934 : val;
        }
        else {
          (!/^\s*$/.test(val));
          val = (parseInt(val) > 2934) ? 2934 : val;
        }
        $(this).val(val);
      });

}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input id="mlat" type="text" name="mlat" maxlength="4" onkeypress="return numonly(this,event)"><br>
<input type="text" name="mlon" id="mlon" maxlength="4"  onkeypress="return numonly(this,event)">

javascript regex expression

Answer 1

Answer №1

I need to create a regular expression for an input field that only allows four numbers, not exceeding 2934, but also accepts negative numbers like -2394.

Instead of using regex, you can do the following:

var minValue = -2394;
var maxValue = 2934;    
var val = +$(this).val().replace(/[^0-9-]+/g,""); //using a custom regex to remove non-numeric characters
var isValid = !isNaN( val ) && val < maxValue && val > minValue ;

It seems like you want to set these values as the upper and lower bounds:

if ( !isNaN( val ) )
{
    var finalVal  = isValid ? val : (val < 0 ? minValue  : maxValue);
}

Answer 2

I need to create a regular expression for an input field that only allows four numbers, not exceeding 2934, but also accepts negative numbers like -2394.

Instead of using regex, you can do the following:

var minValue = -2394;
var maxValue = 2934;    
var val = +$(this).val().replace(/[^0-9-]+/g,""); //using a custom regex to remove non-numeric characters
var isValid = !isNaN( val ) && val < maxValue && val > minValue ;

It seems like you want to set these values as the upper and lower bounds:

if ( !isNaN( val ) )
{
    var finalVal  = isValid ? val : (val < 0 ? minValue  : maxValue);
}

Answer 3

Answer №2

Here is a method you can use:

<html>
<head>
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
</head>

<body>
<input id="mlat" type="text" name="mlat" maxlength="5" onkeypress="return numonly(this,event)"><br>
<input type="text" name="mlon" id="mlon" maxlength="5"  onkeypress="return numonly(this,event)">
<script type="text/javascript">

function numonly(myfield, e, dec){

  // max input value of 4196 x 4196
  $("#mlat").keyup(function() {
    var val = $(this).val().replace(/-?\d+[^0-9]+/,"");
    if (val => 2934){
      !/^\s*$/.test(val);
      if (val > 0) {
        val = (parseInt(val) > 2934) ? 2934 : val;
      }else{
        val = (parseInt(val) > -2394) ? val : -2394;
      }

    }
    else {
      (!/^\s*$/.test(val));
      if (val > 0) {
        val = (parseInt(val) > 2934) ? 2934 : val;
      }else{
        val = (parseInt(val) > -2394) ? val : -2394;
      }
    }
    $(this).val(val);
  })
};


</script>
</body>
</html>

To accommodate the - sign in the input tag, remember to replace the maxlength with 5.

Answer 4

Here is a method you can use:

<html>
<head>
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
</head>

<body>
<input id="mlat" type="text" name="mlat" maxlength="5" onkeypress="return numonly(this,event)"><br>
<input type="text" name="mlon" id="mlon" maxlength="5"  onkeypress="return numonly(this,event)">
<script type="text/javascript">

function numonly(myfield, e, dec){

  // max input value of 4196 x 4196
  $("#mlat").keyup(function() {
    var val = $(this).val().replace(/-?\d+[^0-9]+/,"");
    if (val => 2934){
      !/^\s*$/.test(val);
      if (val > 0) {
        val = (parseInt(val) > 2934) ? 2934 : val;
      }else{
        val = (parseInt(val) > -2394) ? val : -2394;
      }

    }
    else {
      (!/^\s*$/.test(val));
      if (val > 0) {
        val = (parseInt(val) > 2934) ? 2934 : val;
      }else{
        val = (parseInt(val) > -2394) ? val : -2394;
      }
    }
    $(this).val(val);
  })
};


</script>
</body>
</html>

To accommodate the - sign in the input tag, remember to replace the maxlength with 5.

Answer 5

Answer №3

function limitNumbers(myfield, e, dec){
  // the maximum input value allowed is 4196 x 4196
  $("#mlat,#mlon").keyup(function() {
    var val = $(this).val().replace(/[^0-9-]+,"");
    if (parseInt(val) > 2934){
      val = (parseInt(val) > 2934) ? 2934 : val;
    }
    else {
      val = (parseInt(val) < -2934) ? -2934 : val;
    }
    $(this).val(val);
  });
}

Extend the max length to 5 to accommodate the use of '-'

<input id="mlat" type="text" name="mlat" maxlength="5" onkeypress="return numonly(this,event)"><br>
<input type="text" name="mlon" id="mlon" maxlength="5"  onkeypress="return numonly(this,event)">

Answer 6

function limitNumbers(myfield, e, dec){
  // the maximum input value allowed is 4196 x 4196
  $("#mlat,#mlon").keyup(function() {
    var val = $(this).val().replace(/[^0-9-]+,"");
    if (parseInt(val) > 2934){
      val = (parseInt(val) > 2934) ? 2934 : val;
    }
    else {
      val = (parseInt(val) < -2934) ? -2934 : val;
    }
    $(this).val(val);
  });
}

Extend the max length to 5 to accommodate the use of '-'

<input id="mlat" type="text" name="mlat" maxlength="5" onkeypress="return numonly(this,event)"><br>
<input type="text" name="mlon" id="mlon" maxlength="5"  onkeypress="return numonly(this,event)">

Validate with regex that the string contains only numbers and a negative sign at the beginning

Answer №1

Answer №2

Answer №3

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