js代码

<script type="text/javascript">
    function _class(str) {
        return document.getElementsByClassName(str);
    }
    var fontstring = _class("fontString")[0];
    var strExample = "网上打字测试，点开始之后可以开始打字，按下第一个键之后开始计时，" +
        "打字结束之后可以按计算速度计算你刚才打字的速度，下方同时显示错误的字数、经过的时间。" +
        "打错的字是红色显示，正确的是蓝色字，还没有打的是黑色。"
    var costTime = _class("time")[0];
    var costtime = 0;
    var errorcount = 0;
    var timer;
    var haveEnter = false;
    var fonttextarea = _class("fontTextarea")[0];
    var beginbtn = _class("beginBtn")[0],
        finishbtn = _class("finishBtn")[0];
    var error = _class("error")[0],
        speed = _class("speed")[0];
    window.onload = function () {
        fonttextarea.disabled = true;
        fontstring.innerText = strExample;
        fonttextarea.onkeydown = function () {
            var strcount = 0;
            var str = "";
            if (fonttextarea.value == "") return;
            if (!haveEnter) {
                haveEnter = true;
                costtime = 0;
                timer = setInterval(function () {
                    showtimeFun();
                }, 1000);
            }
            for (var i = 0; i < strExample.length - 1; i++) {
                if (i < fonttextarea.value.length) {
                    if (fonttextarea.value.slice(i, i + 1) == strExample.slice(i, i + 1)) {
                        str = str + "<span class='rightfont'>" + strExample.slice(i, i + 1) + "</span>";
                    }
                    else {
                        str = str + "<span class='errorfont'>" + strExample.slice(i, i + 1) + "</span>";
                        strcount++;
                    }
                }
                else {
                    str = str + strExample.slice(i, i + 1);
                }
            }
            errorcount = strcount;
            fontstring.innerHTML = str;
            error.innerText = errorcount;
        }
        function showtimeFun() {
            costtime++;
            costTime.innerText = costtime;
        }
        beginbtn.onclick = function () {
            errorcount = 0;
            fontstring.innerText = strExample;
            fonttextarea.value = "";
            fonttextarea.disabled = false;
            fonttextarea.focus();
            error.innerText = errorcount;
            speed.innerText = "0";
        }
        finishbtn.onclick = function () {
            clearInterval(timer);
            costTime.innerText = 0;
            fonttextarea.disabled = true;
            var sp = 0;
            if (fonttextarea.value == "") {
                return sp;
            } else {
                sp = Number(fonttextarea.value.length * 60 / costtime).toFixed(2);
                speed.innerText = sp;
                haveEnter = false;
            }
        }
    }
</script>