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BOOK: Professional JavaScript for Web Developers ISBN: 978-0-7645-7908-0
This is the forum to discuss the Wrox book Professional JavaScript for Web Developers by Nicholas C. Zakas; ISBN: 9780764579080
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Old November 17th, 2005, 10:35 AM
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Default Prevent user input while JS executes

I have a text field that prevents non-numeric input and formats a social security number with dashes. (999-99-9999) Example is below.

I have encountered a problem where if I input a ssn (eg. "123456789") then delete the text "3-45-6" (text display is now "12789") then insert the missing numbers "3456" too quickly the numbers are in the wrong order. The display as "123-46-5789". 6 and 5 are transposed. I have tried this a number of times so I know I am not fat fingering. I must type very fast for this to happen but it does occur with regularity. If I type slower it works fine. I tried disabling the field in my reformat script, but it did not fix it.

Any ideas as to how I can prevent this from happening?





  function formatSSN(formName, inputName){
    //format input in 999-99-9999 format

    //reformat if a character key was entered
    if(window.event.keyCode > 47){

      inputField = eval( 'document.'+ formName +'.' + inputName );

      var ssnValue = inputField.value;

      //save caret position
      var caretPos = getCaretPosition(inputField);
      if(caretPos == 4|| caretPos == 7 || caretPos >= ssnValue.length)
        caretPos = caretPos + 1;

//**disabled input here but does not prevent bad input
//inputField.disabled = true; //prevent user input while js is executing

      //strip out any non-numeric content
      ssnValue = removeNonNumerics(ssnValue);

      //add hyphen
      ssnValue = addFormatHyphen(ssnValue);

      inputField.value = ssnValue;

//**disable attempt did not prevent error
//inputField.disabled = false;

      //reposition the cursor if not at beginning
      if(caretPos > 1){
        setSelectionRange(inputField, caretPos, caretPos);


  function addFormatHyphen(ssn){
    var ssnLength = ssn.length;

    //add format hyphen
    if(ssnLength > 5){
      ssn =
      (ssn.substr(0,3) + "-"+
      ssn.substr(3,2) + "-" +
    }else if(ssnLength > 3){
      ssn =
      ssn.substr(0,3) + "-"+
    return ssn;

  function removeNonNumerics(checkString){
    rExp = /[^0-9]/g;
    return checkString.replace(rExp,"");

  function getCaretPosition(objTextBox){

    var objTextBox = window.event.srcElement;

    var i = objTextBox.value.length;

    if (objTextBox.createTextRange){
        objCaret = document.selection.createRange().duplicate();
        while (objCaret.parentElement()==objTextBox &&
               objCaret.move("character",1)==1) --i;
    return i;

  function setSelectionRange(input, selectionStart, selectionEnd) {
    if (input.setSelectionRange) {
      input.setSelectionRange(selectionStart, selectionEnd);
    else if (input.createTextRange) {
      var range = input.createTextRange();
      range.moveEnd('character', selectionEnd);
      range.moveStart('character', selectionStart);

<form name=myForm method=POST >
Social Security <input type=text name=SSN onkeyup="formatSSN('myForm', this.name)" size=11 maxlength=11 >


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