Validation #3: Number Check

Discussion

function validate()
{
    // Version 3.0 will support
    // (typeof(parseInt(document.forms[0].F1.value)) == 'Number')
    // for now, we must assume that there is a number there
    // or else go through more elaborate parsing
    
    if (document.forms[0].F1.value.length == 0) 
    {
        alert('You must enter a number')
        return false
    }
    
    // Recover whatever value we can get
    var aValue = parseInt(document.forms[0].F1.value)
    if(isNaN(aValue))
        aValue = 0;
    
    // Check that it is in range.
    if ((aValue < 1) || (aValue > 100))
    {
        alert('Values must range between 1 and 100')
        
        // prepare field to be overwritten
        document.forms[0].F1.focus()
        document.forms[0].F1.select()
        return false
    }
    else 
        return true
}