Question

First the code:

function searchItems(){
var noParameters = new Boolean(0);
var formFields = $('form')[0].elements;
for(i=0;1<formFields.length;i++){
    if(formFields[i].type == 'text'){
        if(!(formFields[i].value)){
            noParameters = 0;
        }
    }
}
alert(noParameters.valueOf());
}

This function is called on a form submit. It’s purpose is to see if all form fields of type ‘text’ have no value (empty input boxes).

I do not get an alert when I think I should. The boolean variable is initialized when it is declared, so there is a value in it. The if statements all work as they should, I have checked repeatedly. The only error I have in my browser is “type is null or not an object” which is on the line comparing the form field type to ‘text’.

I have tried different syntax for the alert with no success: noParameters.toString(), assigning noParameters.valueOf() to a variable and then alerting that, ‘true’ and ‘false’ instead of 0 and 1. Why does my alert not show?

Answer 1

You have an infinite loop because the condition 1 < formFields.length is always true. Yet, i gets increased every time, until formFields[i] evaluates to null and you get the exception because you can’t access a type property of a non-object.

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To your question: new Boolean(0); creates an absolutely unnecessary Object wrapper for the value false. Don’t use it. Inside the loop, you eventually assign 0 to the variable. JavaScript is weak-typed so this is syntactically valid, but still odd.

Then, in the alert you use the .valueOf() method. For the number 0 this will work because it is implicitly converted to a Number instance, but uncommon as well. If you’d used just a boolean value, you would not need it.