SOURCE

//字符倒序
function countNumbers(str) {
	var sum = 0;
    //字符串去空格
    str = str.replace(/\s*/g,"");
	// 分割字符串为单字符数组
	var arr = str.split("");
	// 遍历数组
	for(var i in arr) {
            sum++;
    }
    return sum;
}

var stringValue = "Rome was not built in a day";
document.write(countNumbers(stringValue));