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I have the following Javascript code:

function checkIfValid(){
    var form = document.createuserform;
    var valid = new Array();

    for(i = 0; i < 4; i++){
    valid[i] = false;
    }

    if(form.fName.value == ""){
    form.getElementById('fNameStatus').innerHTML = "Please Enter Your First Name";
    valid[0] = false;
    }else{
    document.getElementById('fNameStatus').innerHTML = "";
    valid[0] = true;
    }

    if(form.lName.value == ""){
    valid[1] = false;
    }else{
    valid[1] = true;
    }

    if(!isValidEmail){
    valid[2] = false;   
    }else{
    valid[2] = true;
    }

    if(form.pass.value == ""){
    valid[3] = false;
    }else{
    valid[3] = true;
    }

    if(checkIfValid(valid)){
    form.submit();
    }
}

function checkIfValid(arr){
    for(i = 0; i < arr.length; i++){
    if(!arr[i]){
        return false;
    }
    }
    return true;
}

function isValidEmail(){
    var x=document.forms["createuserform"]["email"].value
    var atpos=x.indexOf("@");
    var dotpos=x.lastIndexOf(".");
    if (atpos<1 || dotpos<atpos+2 || dotpos+2>=x.length)
    {
    return false;
    }
    return true;
}

Upon running I get the following error in firefox error console "arr is undefined line 46". An

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you have two functions with the same name, and what about moving the var valid = new Array(); line outside of the function – Robot Woods Jul 27 '11 at 18:31
Line 43 in your code example is return false. – Linus Kleen Jul 27 '11 at 18:32
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3 Answers

up vote 2 down vote accepted

It looks like you might be trying to first call a no-argument version of checkIfValid in which an overloaded version of the same function is called with a single argument.

JavaScript does not have function overloading.

The last definition is used whenever checkIfValid is invoked.

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sorry I don;t understand? Where am I overloading the method? I have it defined only once and am calling it once...I just want to pass the valid array into the checkIfValid function – user559142 Jul 27 '11 at 18:37
1  
The first function in your example is function checkIfValid(); the second function in your example is function checkIfValid(arr). Those names are the same, which is an error. Your first function can never be called. – lwburk Jul 27 '11 at 18:53
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up vote 0 down vote

As others have said, you can't have the same named function with different parameters in javascript and expect both to work. Only the last one defined is active. You can, however have a single function that checks to see what parameters were passed and act accordingly. So, you could replace both of your functions with this single function:

function checkIfValid(arr){
    // if array passed, check it
    if (arr) {
        for(i = 0; i < arr.length; i++){
            if(!arr[i]){
                return false;
            }
        }
        return true;
    }

    // if no array passed, check our form
    var form = document.createuserform;
    var valid = new Array();

    for(i = 0; i < 4; i++){
    valid[i] = false;
    }

    if(form.fName.value == ""){
    form.getElementById('fNameStatus').innerHTML = "Please Enter Your First Name";
    valid[0] = false;
    }else{
    document.getElementById('fNameStatus').innerHTML = "";
    valid[0] = true;
    }

    if(form.lName.value == ""){
    valid[1] = false;
    }else{
    valid[1] = true;
    }

    if(!isValidEmail){
    valid[2] = false;   
    }else{
    valid[2] = true;
    }

    if(form.pass.value == ""){
    valid[3] = false;
    }else{
    valid[3] = true;
    }

    if(checkIfValid(valid)){
    form.submit();
    }
}

Or, if your second function is really just a helper function and not intended to be an overloaded version of the first one, then just change it's name:

function checkIfValid(arr){
    // if no array passed, check our form
    var form = document.createuserform;
    var valid = new Array();

    for(i = 0; i < 4; i++){
    valid[i] = false;
    }

    if(form.fName.value == ""){
    form.getElementById('fNameStatus').innerHTML = "Please Enter Your First Name";
    valid[0] = false;
    }else{
    document.getElementById('fNameStatus').innerHTML = "";
    valid[0] = true;
    }

    if(form.lName.value == ""){
    valid[1] = false;
    }else{
    valid[1] = true;
    }

    if(!isValidEmail){
    valid[2] = false;   
    }else{
    valid[2] = true;
    }

    if(form.pass.value == ""){
    valid[3] = false;
    }else{
    valid[3] = true;
    }

    if(checkIfArrayValid(valid)){
    form.submit();
    }
}

function checkIfArrayValid(arr){
    for(i = 0; i < arr.length; i++){
        if(!arr[i]){
            return false;
        }    
    }
    return true;
}
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up vote 0 down vote

You have the functions checkIfValid(arr) and checkIfValid(). One or the other, not both. Like the other people said, javascript doesn't support function overloading

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