Characters "'" and "f" appear in the textbox, how to correct?

In JavaScript that 'false' with single quotes or "false" are strings, and every string is FALSE .

$(".input-numeric").numeric({
    decimal: false,
    negative:false
});

Here's a good teaching material on the subject: W3Schools: JavaScript Booleans .

Apparently you're using the jQuery.Numeric package. This package has bugs ( see the 'notes' section , and see that the ' enters all fields). He would not use it if he were in his place.

There are two good alternatives:

• <input type="number />" ;
• jQuery.Inputmask .

The changes made to the bug fix were:

Thiago Lunardi's tip: He no longer accepts the letter F, but continues to accept the "'".

$(".input-numeric").numeric({
    decimal: false,
    negative:false
});

Jquery Numeric (Old): Accepted the "" "

$.fn.numeric.keypress = function(e)
{
    // get decimal character and determine if negatives are allowed
    var decimal = $.data(this, "numeric.decimal");
    var negative = $.data(this, "numeric.negative");
    var decimalPlaces = $.data(this, "numeric.decimalPlaces");
    // get the key that was pressed
    var key = e.charCode ? e.charCode : e.keyCode ? e.keyCode : 0;
    // allow enter/return key (only when in an input box)
    if(key == 13 && this.nodeName.toLowerCase() == "input")
    {
        return true;
    }
    else if(key == 13)
    {
        return false;
    }
    //dont allow #, $, %, '
    else if(key == 35 || key == 36 || key == 37){
        return false;
    }

Jquery Numeric (New) has been added to key 39, now blocks the "'":

$.fn.numeric.keypress = function(e)
{
    // get decimal character and determine if negatives are allowed
    var decimal = $.data(this, "numeric.decimal");
    var negative = $.data(this, "numeric.negative");
    var decimalPlaces = $.data(this, "numeric.decimalPlaces");
    // get the key that was pressed
    var key = e.charCode ? e.charCode : e.keyCode ? e.keyCode : 0;
    // allow enter/return key (only when in an input box)
    if(key == 13 && this.nodeName.toLowerCase() == "input")
    {
        return true;
    }
    else if(key == 13)
    {
        return false;
    }
    //dont allow #, $, %, '
    else if(key == 35 || key == 36 || key == 37 || key == 39){
        return false;
    }

Jquery Numeric Control + V (Old): Accepted Control + V

$.fn.numeric.blur = function()
{
    var decimal = $.data(this, "numeric.decimal");
    var callback = $.data(this, "numeric.callback");
    var negative = $.data(this, "numeric.negative");
    var val = this.value;
    if(val !== "")
    {
        var re = new RegExp("^" + (negative?"-?":"") + "\d+$|^" + (negative?"-?":"") + "\d*" + decimal + "\d+$");
        if(!re.exec(val))
        {
            callback.apply(this);
        }
    }
};

Jquery Numeric (New): Now blocks Control + V

$.fn.numeric.blur = function()
{
    var decimal = $.data(this, "numeric.decimal");
    var callback = $.data(this, "numeric.callback");
    var negative = $.data(this, "numeric.negative");
    var val = this.value;
    if(val !== "")
    {
        var re = new RegExp("^" + (negative?"-?":"") + "\d+$|^" + (negative?"-?":"") + "\d*" + decimal + "\d+$");
        if(!re.exec(val))
        {
            callback.apply(this);
            this.value = "";
        }
    }
};