set focus NOT onload

What I am trying to do is verify that a textbox is all numeric, and if it isn't, clear it and set the focus back on the text box. I have gotten it to clear it, but it won't set the focus.

<tr>
<td><input type="text" name="billable_rate" id="billable_rate" onchange="calcTotal(this.value, billable_rate);"></td>
</tr>
<tr>
	<td><input type="text" name="travel_rate" id="travel_rate" onchange="calcTotal(this.value, travel_rate);"></td>
				</tr>

HTML:

function calcTotal(sText, field){
	var ValidChars = "0123456789.";
	var IsNumber=true;
	var Char;
	var total = 0.00;
	var field2 = field.name;

	for (i = 0; i < sText.length && IsNumber == true; i++){
		Char = sText.charAt(i); 
		if (ValidChars.indexOf(Char) == -1){
			IsNumber = false;
		}
	}
	
	if(true == IsNumber){
		var billableRate = document.getElementById("billable_rate").value*1;
		var travelRate = document.getElementById("travel_rate").value*1;
		total = billableRate+travelRate;
		subTotal = document.getElementById('subTotal');
		replaceText(subTotal, total);
	}else{
		alert("not a valid number");
		switch (field2){
			case 'billable_rate':
				document.stuff.billable_rate.value = '';
				var txtBox=document.getElementById("billable_rate");
				if (txtBox==null)txtBox.focus();
			break;
			case 'travel_rate':
				document.stuff.travel_rate.focus();
				document.stuff.travel_rate.value = '';
				
			break;
		}
	}
}

Code (markup):

Any ideas are greatly appreciated. TIA

 

try switching the order of commands - first set the value to an empty string and only after set the focus.

 

I have it doing that under case: billable_rate, and the opposite way under case: 'travel_rate', but neither one work... I don't know why I always have so much trouble with setting the focus.

 

dodgy. anyway - look at this, working with a small hack via a 300ms timeout: http://www.jsfiddle.net/dimitar/kaCEG/2/

(function() {
    var slowFocus = function(what) {
        var timer;
        clearTimeout(timer);
        timer = setTimeout(function() {
            what.focus();
        }, 300);
    };
    
    var calcTotal = function(field) {
        var ValidChars = "0123456789.";
        var sText = field.value;
        var IsNumber=true;
        var Char;
        var total = 0.00;
        var field2 = field.name;
        
        for (i = 0; i < sText.length && IsNumber == true; i++){
            Char = sText.charAt(i);
            if (ValidChars.indexOf(Char) == -1){
                IsNumber = false;
            }
        }
        
        if(IsNumber){
            var billableRate = document.getElementById("billable_rate").value*1;
            var travelRate = document.getElementById("travel_rate").value*1;
            total = billableRate+travelRate;
            subTotal = document.getElementById('subTotal');
            replaceText(subTotal, total);
        } else {
            //alert("not a valid number");
            switch (field2){
                case 'billable_rate':
                    field.value = '';
                    
                    slowFocus(field);
                   
                break;
                case 'travel_rate':
                    field.value = "";
                    slowFocus(field);
                break;
            }
        }
    }
    
    document.getElementById("billable_rate").onchange = function() {
        calcTotal(this);
    };
    
    document.getElementById("travel_rate").onchange = function() {
        calcTotal(this);
    };
})();

Code (javascript):

 

See, thats why you get paid the big bucks