SOURCE

//统计字符串中数字的个数
function countNumber(stringtoCount) 
{
    var numCount = 0;
        for (var i = 0; i < stringtoCount.length; i++)
        {            
            var char = stringtoCount.charAt(i);
            //isNaN()对空格字符会转化为0
            if (char != " " && !isNaN(char))
            {
                numCount++;
            }
        }
        return numCount;
}
document.write(countNumber("37ggih4kjg9 hj7"));