Stop form from submitting if all fields not filled in.

function pattern () {

var yourName = $('input[name="name"]').val(),
    handCircumference = $('input[name="handCirc"]').val(),
    thumbCircumference = $('input[name="thumbCirc"]').val(),
    thumbBaseToIndex = $('input[name="thumbBase"]').val(),
    stitchesPerFourInches = $('input[name="gauge"]').val(),
    needleSize = $('input[name="needles"]').val(),
    yarnUsed = $('input[name="yarn"]').val(),
    inches = $('input[id="inches"]:checked').val("true");

var stsPerCm = parseFloat(stitchesPerFourInches)/10;


if (inches.length > 0) {
var measure = "inches",
    handInches = parseFloat(handCircumference) * 2.5,
    thumbInches = parseFloat(thumbCircumference) * 2.5,
    thumbBase = parseFloat(thumbBaseToIndex),
    palm = (Math.round(thumbBase - .5) * 2 / 2).toFixed(1);} else {
var measure = "cm",
    handInches = parseFloat(handCircumference),
    thumbInches = parseFloat(thumbCircumference),
    thumbBase = parseFloat(thumbBaseToIndex),
    palm = (Math.round(thumbBase - 1.25) * 2 / 2).toFixed(1);
}

var castOn = Math.ceil(stsPerCm * handInches);

if ((castOn % 2 == 0) === true){
var castOn = castOn;
} else {
var castOn = castOn + 1
};

var thumbStitches = Math.ceil(stsPerCm * thumbInches-2);

if ((thumbStitches % 2 != 0) === true){
var thumbStitches = thumbStitches;
} else {
var thumbStitches = thumbStitches + 1
};

if (yourName.length == 0, handCircumference.length == 0, thumbCircumference.length == 0, thumbBaseToIndex.length == 0, stitchesPerFourInches.length == 0,needleSize.length == 0, yarnUsed == 0 ) {
alert("You must fill in all fields or your pattern won't be knittable");}

return '<h2>' + yourName + '\'s Custom Fit Fingerless Mitts Pattern </h2>' +
'<p>You can create more custom fit mitt patterns at http\:\/\/goo.gl\/4uIxfx' +
'</p><p>' +
'<strong>Size\:</strong> ' + 'to fit ' + handCircumference + ' ' + measure + ' hand circumference \(excluding thumb\)' +
'</p>' +
'<h3> Materials </h3>' +
'<p>' +
'<strong>Needles\:</strong> A set of size ' + needleSize + ' double pointed needles and a set of DPNs one or two sizes smaller for the ribbing' +
'</p><p>' +
'<strong>Yarn\:</strong> ' + yarnUsed + '' + 
'</p><p>' +
'<strong>Tension\:</strong> ' + stitchesPerFourInches + ' sts per 10cm\/4\" over stocking stitch on ' + needleSize + ' needles' +
'</p>' +
'<h3> Abbreviations </h3>' + 
'<p>' +
'M1 = Make 1 stitch by putting your needle under the thread that lies between stitches, twist it (to avoid making a hole), and knit it.' +
'</p><p>' +
'P2tog = Purl 2 stitches together.' +
'</p>' +
'<h3> Pattern </h3>' +
'<p>' +
'Using smaller needles, cast on ' + 
castOn + 
' sts, and join for knitting in the round. Place a marker at the beginning of the round. ' +
'</p><p>' +
'Work 5cm or 2\" k1, p1 rib.' +
'</p><p>' +
'Change to larger needles and work 2.5cm or 1\" of stocking stitch \(knit every round\).' +
'</p><p>' + 
'Make thumb gusset as follows\:' +
'</p><p>' +
'K1, m1, k1, m1, k to end of round' +
'</p><p>' +
'Knit 1 round' +
'</p><p>' +
'K1, m1, k3, m1, k to end of round' +
'</p><p>' +
'Knit 1 round' +
'</p><p>' +
'K1, m1, k5, m1, k to end of round' +
'</p><p>' +
'Knit 1 round' +
'</p><p>' +
'Continue increasing in this manner \(working 2 more stitches between the m1\'s on every second round\) until you reach \"K1, m1, k' + 
thumbStitches + 
', m1, k to end of round' +
'</p><p>' +
'Next round\: K1, put next ' + (thumbStitches+2) + ' sts onto a holder, cast on 1 st, k to the end of the round.' + 
'</p><p>' +
'Continue working rounds in stocking stitch for ' + palm + ' ' + measure + '' +
'</p><p>' +
'Change to smaller needles and work 1.25cm or 1\/2\" in k1, p1 rib. Cast off neatly in rib.' +
'</p><p>' +
'<strong>Thumb</strong>' +
'</p><p>' +
'Using smaller needles work k1, p1 rib across the stitches you put on a holder, beginning with a purl stitch, then pick up 3sts at the top of the thumb \(where you cast on 1 st after finishing the thumb gusset\).' +
'</p><p>' +
'Place a marker for the beginning of the round.' +
'</p><p>' +
'Next round\: Work rib to the last 4sts, P2tog, k1, remove the end of round marker and purl the last stitch together with the 1st stitch of the next round. Replace the end of round marker.' +
'</p><p>' +
'Work 1.25cm or 1\/2\" of k1, p1 rib \(beginning with a knit stitch this time!\), cast off loosely.' +
'</p><p>' +
'<strong>Finishing</strong>' +
'</p><p>' +
'Darn in all loose ends, wash and block.' +
'</p><p>' +
'Copyright Sarah Bradberry June 2005. All rights reserved.\n'
}

$("#makepattern").click(function (event) {
    return pattern();
    }
    );

$( "#makepattern" ).click(function( event ) {
    event.preventDefault();
  $( "#patternResult" ).html( event.result );
}
);

$( "#makepattern" ).click(function() {
  $("#patternCreate" ).hide( );
}
);