$("#chartModal").keypress( function (e) {
if (e.which != 8 && e.which != 0 && e.which != 43 && e.which != 45 && e.which != 46 && (e.which < 48 || e.which > 57)) {
return false;
}
});
This accept +, - & . in between the number, which is not a number.
Try with this
$(document).ready(function () {
$('#chartModal').keypress(function(e) {
var key = e.charCode || e.keyCode || 0;
var keychar = String.fromCharCode(key);
if ( ((key == 8 || key == 9 || key == 46 || key == 35 || key == 36 || (key >= 37 && key <= 40)) && e.charCode==0) /* backspace, end, begin, top, bottom, right, left, del, tab */
|| (key >= 48 && key <= 57) ) { /* 0-9 */
return;
} else {
e.preventDefault();
}
});
});