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小demo原生js同步翻译，可以玩玩儿

由 故事扮演 提交于 2020-01-21 18:38:28

1. 背景：

平时不知道用js写什么练手，这里就写了一个类似百度翻译的小demo。大家可以平时没事儿了看看书，写写像这种类型的小demo,调用以下公开的api即可。对于学生党，能进入学校实验室做项目更好。进不去的，平时写写小demo练练也不差。(我为什么没在实验室)

2. demo前准备工作：

  1. 页面布局

  2. 了解百度翻译API，所需配置参数

  3. 准备 MD5.js 加密算法函数（百度自己搜）

  4. 写js代码

3. 步骤：

1. 页面布局：
布局就不说了，直接贴图上代码：

可进行语言切换

html代码：

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title></title>
  <link rel="stylesheet" type="text/css" href="css/style.css">
</head>
<body>
  <div id="main">
    <div class="left">
      <div class="title">
        要翻译为：
        <span class="lang">英文</span>
        <ul class="ul1">
          <li data-lang="en">英语</li>
          <li data-lang="zh">中文</li>
          <li data-lang="jp">日语</li>
          <li data-lang="kor">韩语</li>
          <li data-lang="fra">法语</li>
          <li data-lang="ru">俄语</li>
          <li data-lang="de">德语</li>
        </ul>
      </div>
      <textarea class="text" placeholder="要翻译的单词/句子" value=""></textarea>
    </div>
    <div class="right">
      <div class="title">翻译结果：</div>
      <div class="cont"></div>
    </div>
    <div class="bottom">
      <button class="reset">清除</button>
      <button class="trans">翻译</button>
    </div>
  </div>
  <script src="js/MD5.js"></script>
  <script src="js/script.js"></script>
</body>
</html>

css代码：

*{
  margin: 0;
  padding: 0;
  font-family: "微软雅黑";
}
html,body {
  height: 100%;
}
li {
  list-style: none;
}
body {
  overflow: hidden;
}
#main {
  width: 1000px;
  height: 80%;
  margin: 5% auto;
}
#main .left {
  float: left;
  width: 350px;
  height:330px;
  margin: 50px 0 0 50px;
  background-color: #fff;
  border: 1px solid #000;
  box-sizing: border-box;
  color: #fff;
  border-top-left-radius: 15px;
  border-top-right-radius: 15px;
}
#main .right {
  float: right;
  width: 350px;
  height: 330px;
  margin: 50px 50px 0 0;
  background-color: #fff;
  box-sizing: border-box;
  border: 1px solid #000;
  border-top-left-radius: 15px;
  border-top-right-radius: 15px;
}
#main .title {
  width: 100%;
  height: 40px;
  background-color: #333;
  line-height: 40px;
  text-indent: 20px;
  position: relative;
  color: #fff;
  border-top-left-radius: 15px;
  border-top-right-radius: 15px;
}
#main .lang {
  height: 40px;
  line-height: 40px;
  text-indent: 20px;
  letter-spacing: 2px;
  text-decoration: underline;
  color: #58a;
  cursor: pointer;
}
#main .lang:hover {
  text-decoration: none;
  color: #eee;
}
#main .text {
  width: 100%;
  height: 288px;
  padding: 20px;
  box-sizing: border-box;
  resize: none;
  outline: none;
  border: none;
}
#main .right .cont {
  width: 100%;
  height: 295px;
  padding: 20px;
  box-sizing: border-box;
}
#main .bottom {
  float: left;
  width: 100%;
  height: 40px;
  margin-top: 60px;
}
#main .bottom button {
  float: right;
  width: 65px;
  height: 35px;
  line-height: 35px;
  letter-spacing: 2px;
  border: none;
  margin-right: 50px;
  border-radius: 3px;
  outline: none;
  cursor: pointer;
  color: #eee;
  background-color: #333;
}
#main ul {
  width: 100%;
  padding: 20px 15px 0 20px;
  box-sizing: border-box;
  position: absolute;
  background: blue;
  background-color: #fff;
  border-bottom: 1px solid #333;
  display: none;
}
#main ul li {
  float:left;
  text-indent: 0;
  text-align: center;
  padding: 0 10px;
  margin: 0 10px;
  margin-bottom: 20px;
  border: 1px solid #000;
  border-radius: 5px;
  box-sizing: border-box;
  color: #333;
  cursor: pointer;
}
#main ul li:hover {
  background-color: #333;
  color: #fff;
}

2，了解百度翻译API
这只只对所配置的参数做一介绍，官方API也有做解释：

进入百度翻译，左下角如图：

点击百度翻译开放平台：

  • q是你要翻译的字符串

  • from是你在输入时的语言

  • to是你要翻译成什么语言

  • appid是你申请的百度翻译测试账号（注册后秒发）

  • salt是一个随机数，这里用事件表示

  • sign是对拼接的字符串的MD5加密，至于拼接的字符串其实就是： 待加密字符串 =
    appid+q+salt+秘钥（申请账号时密码也会给你） 最后把 待价密 的字符串传入MD5函数，返回sign.

完整流程如图：

3.准备MD5加密函数（可以百度自己搜，这里直接附代码）

MD5加密字符串：

var MD5 = function (string) {

    function RotateLeft(lValue, iShiftBits) {
        return (lValue<<iShiftBits) | (lValue>>>(32-iShiftBits));
    }

    function AddUnsigned(lX,lY) {
        var lX4,lY4,lX8,lY8,lResult;
        lX8 = (lX & 0x80000000);
        lY8 = (lY & 0x80000000);
        lX4 = (lX & 0x40000000);
        lY4 = (lY & 0x40000000);
        lResult = (lX & 0x3FFFFFFF)+(lY & 0x3FFFFFFF);
        if (lX4 & lY4) {
            return (lResult ^ 0x80000000 ^ lX8 ^ lY8);
        }
        if (lX4 | lY4) {
            if (lResult & 0x40000000) {
                return (lResult ^ 0xC0000000 ^ lX8 ^ lY8);
            } else {
                return (lResult ^ 0x40000000 ^ lX8 ^ lY8);
            }
        } else {
            return (lResult ^ lX8 ^ lY8);
        }
    }

    function F(x,y,z) { return (x & y) | ((~x) & z); }
    function G(x,y,z) { return (x & z) | (y & (~z)); }
    function H(x,y,z) { return (x ^ y ^ z); }
    function I(x,y,z) { return (y ^ (x | (~z))); }

    function FF(a,b,c,d,x,s,ac) {
        a = AddUnsigned(a, AddUnsigned(AddUnsigned(F(b, c, d), x), ac));
        return AddUnsigned(RotateLeft(a, s), b);
    };

    function GG(a,b,c,d,x,s,ac) {
        a = AddUnsigned(a, AddUnsigned(AddUnsigned(G(b, c, d), x), ac));
        return AddUnsigned(RotateLeft(a, s), b);
    };

    function HH(a,b,c,d,x,s,ac) {
        a = AddUnsigned(a, AddUnsigned(AddUnsigned(H(b, c, d), x), ac));
        return AddUnsigned(RotateLeft(a, s), b);
    };

    function II(a,b,c,d,x,s,ac) {
        a = AddUnsigned(a, AddUnsigned(AddUnsigned(I(b, c, d), x), ac));
        return AddUnsigned(RotateLeft(a, s), b);
    };

    function ConvertToWordArray(string) {
        var lWordCount;
        var lMessageLength = string.length;
        var lNumberOfWords_temp1=lMessageLength + 8;
        var lNumberOfWords_temp2=(lNumberOfWords_temp1-(lNumberOfWords_temp1 % 64))/64;
        var lNumberOfWords = (lNumberOfWords_temp2+1)*16;
        var lWordArray=Array(lNumberOfWords-1);
        var lBytePosition = 0;
        var lByteCount = 0;
        while ( lByteCount < lMessageLength ) {
            lWordCount = (lByteCount-(lByteCount % 4))/4;
            lBytePosition = (lByteCount % 4)*8;
            lWordArray[lWordCount] = (lWordArray[lWordCount] | (string.charCodeAt(lByteCount)<<lBytePosition));
            lByteCount++;
        }
        lWordCount = (lByteCount-(lByteCount % 4))/4;
        lBytePosition = (lByteCount % 4)*8;
        lWordArray[lWordCount] = lWordArray[lWordCount] | (0x80<<lBytePosition);
        lWordArray[lNumberOfWords-2] = lMessageLength<<3;
        lWordArray[lNumberOfWords-1] = lMessageLength>>>29;
        return lWordArray;
    };

    function WordToHex(lValue) {
        var WordToHexValue="",WordToHexValue_temp="",lByte,lCount;
        for (lCount = 0;lCount<=3;lCount++) {
            lByte = (lValue>>>(lCount*8)) & 255;
            WordToHexValue_temp = "0" + lByte.toString(16);
            WordToHexValue = WordToHexValue + WordToHexValue_temp.substr(WordToHexValue_temp.length-2,2);
        }
        return WordToHexValue;
    };

    function Utf8Encode(string) {
        string = string.replace(/\r\n/g,"\n");
        var utftext = "";

        for (var n = 0; n < string.length; n++) {

            var c = string.charCodeAt(n);

            if (c < 128) {
                utftext += String.fromCharCode(c);
            }
            else if((c > 127) && (c < 2048)) {
                utftext += String.fromCharCode((c >> 6) | 192);
                utftext += String.fromCharCode((c & 63) | 128);
            }
            else {
                utftext += String.fromCharCode((c >> 12) | 224);
                utftext += String.fromCharCode(((c >> 6) & 63) | 128);
                utftext += String.fromCharCode((c & 63) | 128);
            }

        }

        return utftext;
    };

    var x=Array();
    var k,AA,BB,CC,DD,a,b,c,d;
    var S11=7, S12=12, S13=17, S14=22;
    var S21=5, S22=9 , S23=14, S24=20;
    var S31=4, S32=11, S33=16, S34=23;
    var S41=6, S42=10, S43=15, S44=21;

    string = Utf8Encode(string);

    x = ConvertToWordArray(string);

    a = 0x67452301; b = 0xEFCDAB89; c = 0x98BADCFE; d = 0x10325476;

    for (k=0;k<x.length;k+=16) {
        AA=a; BB=b; CC=c; DD=d;
        a=FF(a,b,c,d,x[k+0], S11,0xD76AA478);
        d=FF(d,a,b,c,x[k+1], S12,0xE8C7B756);
        c=FF(c,d,a,b,x[k+2], S13,0x242070DB);
        b=FF(b,c,d,a,x[k+3], S14,0xC1BDCEEE);
        a=FF(a,b,c,d,x[k+4], S11,0xF57C0FAF);
        d=FF(d,a,b,c,x[k+5], S12,0x4787C62A);
        c=FF(c,d,a,b,x[k+6], S13,0xA8304613);
        b=FF(b,c,d,a,x[k+7], S14,0xFD469501);
        a=FF(a,b,c,d,x[k+8], S11,0x698098D8);
        d=FF(d,a,b,c,x[k+9], S12,0x8B44F7AF);
        c=FF(c,d,a,b,x[k+10],S13,0xFFFF5BB1);
        b=FF(b,c,d,a,x[k+11],S14,0x895CD7BE);
        a=FF(a,b,c,d,x[k+12],S11,0x6B901122);
        d=FF(d,a,b,c,x[k+13],S12,0xFD987193);
        c=FF(c,d,a,b,x[k+14],S13,0xA679438E);
        b=FF(b,c,d,a,x[k+15],S14,0x49B40821);
        a=GG(a,b,c,d,x[k+1], S21,0xF61E2562);
        d=GG(d,a,b,c,x[k+6], S22,0xC040B340);
        c=GG(c,d,a,b,x[k+11],S23,0x265E5A51);
        b=GG(b,c,d,a,x[k+0], S24,0xE9B6C7AA);
        a=GG(a,b,c,d,x[k+5], S21,0xD62F105D);
        d=GG(d,a,b,c,x[k+10],S22,0x2441453);
        c=GG(c,d,a,b,x[k+15],S23,0xD8A1E681);
        b=GG(b,c,d,a,x[k+4], S24,0xE7D3FBC8);
        a=GG(a,b,c,d,x[k+9], S21,0x21E1CDE6);
        d=GG(d,a,b,c,x[k+14],S22,0xC33707D6);
        c=GG(c,d,a,b,x[k+3], S23,0xF4D50D87);
        b=GG(b,c,d,a,x[k+8], S24,0x455A14ED);
        a=GG(a,b,c,d,x[k+13],S21,0xA9E3E905);
        d=GG(d,a,b,c,x[k+2], S22,0xFCEFA3F8);
        c=GG(c,d,a,b,x[k+7], S23,0x676F02D9);
        b=GG(b,c,d,a,x[k+12],S24,0x8D2A4C8A);
        a=HH(a,b,c,d,x[k+5], S31,0xFFFA3942);
        d=HH(d,a,b,c,x[k+8], S32,0x8771F681);
        c=HH(c,d,a,b,x[k+11],S33,0x6D9D6122);
        b=HH(b,c,d,a,x[k+14],S34,0xFDE5380C);
        a=HH(a,b,c,d,x[k+1], S31,0xA4BEEA44);
        d=HH(d,a,b,c,x[k+4], S32,0x4BDECFA9);
        c=HH(c,d,a,b,x[k+7], S33,0xF6BB4B60);
        b=HH(b,c,d,a,x[k+10],S34,0xBEBFBC70);
        a=HH(a,b,c,d,x[k+13],S31,0x289B7EC6);
        d=HH(d,a,b,c,x[k+0], S32,0xEAA127FA);
        c=HH(c,d,a,b,x[k+3], S33,0xD4EF3085);
        b=HH(b,c,d,a,x[k+6], S34,0x4881D05);
        a=HH(a,b,c,d,x[k+9], S31,0xD9D4D039);
        d=HH(d,a,b,c,x[k+12],S32,0xE6DB99E5);
        c=HH(c,d,a,b,x[k+15],S33,0x1FA27CF8);
        b=HH(b,c,d,a,x[k+2], S34,0xC4AC5665);
        a=II(a,b,c,d,x[k+0], S41,0xF4292244);
        d=II(d,a,b,c,x[k+7], S42,0x432AFF97);
        c=II(c,d,a,b,x[k+14],S43,0xAB9423A7);
        b=II(b,c,d,a,x[k+5], S44,0xFC93A039);
        a=II(a,b,c,d,x[k+12],S41,0x655B59C3);
        d=II(d,a,b,c,x[k+3], S42,0x8F0CCC92);
        c=II(c,d,a,b,x[k+10],S43,0xFFEFF47D);
        b=II(b,c,d,a,x[k+1], S44,0x85845DD1);
        a=II(a,b,c,d,x[k+8], S41,0x6FA87E4F);
        d=II(d,a,b,c,x[k+15],S42,0xFE2CE6E0);
        c=II(c,d,a,b,x[k+6], S43,0xA3014314);
        b=II(b,c,d,a,x[k+13],S44,0x4E0811A1);
        a=II(a,b,c,d,x[k+4], S41,0xF7537E82);
        d=II(d,a,b,c,x[k+11],S42,0xBD3AF235);
        c=II(c,d,a,b,x[k+2], S43,0x2AD7D2BB);
        b=II(b,c,d,a,x[k+9], S44,0xEB86D391);
        a=AddUnsigned(a,AA);
        b=AddUnsigned(b,BB);
        c=AddUnsigned(c,CC);
        d=AddUnsigned(d,DD);
    }

    var temp = WordToHex(a)+WordToHex(b)+WordToHex(c)+WordToHex(d);

    return temp.toLowerCase();
}

加密：

发送请求时别忘了在参数最后面加上一个callback参数用来接收返回值

callback函数：

function fn(str) {
  var result = document.querySelector(".right .cont");
  result.innerHTML = str.trans_result[0].dst;
}

4.写js

这里简单的逻辑就不说了，说说这里的接口请求的实现和实现实时翻译的逻辑（每输入一两个字就会主动给你翻译）。首先这个列子的核心就是jsonp的跨域请求原理很简单，就是每次请求都给他创建一个<script>标签插入body, 每次给标签的src传入不同的参数，待服务器给你返回数据，最终拿到数据渲染到页面。这里要提醒的是要给请求的参数最后面加上一个回调函数，返回过来的数据客户端可以从回调函数中拿取。其次就是实时翻译，原理就是在敲键盘时每次按键抬起时隔一定的时间去请求，那就是键盘事件加上setInterval();每隔500ms去请求。

整个过程的代码如下：

(function() {
  var title = document.querySelector(".left .title .lang"),
      ul = document.querySelector(".ul1"),
      lis = document.querySelectorAll(".ul1 li"),
      text = document.querySelector(".left .text"),
      result = document.querySelector(".right .cont"),
      reset = document.querySelector(".bottom .reset"),
      trans = document.querySelector(".bottom .trans"),
      key = true,
      length = lis.length,
      lang = "en",
      timer = null;

  function langShow() {
    if (key == true) {
      ul.style.display = "block";
      key = false;
    } else {
      ul.style.display = "none";
      key = true;
    }
  }

  function changeLang() {
    lang = this.getAttribute('data-lang');
    title.innerHTML = this.innerHTML;
    this.parentNode.style.display = "none";
    key = true;
  }

  function createScript(src) {
    var script = document.createElement('script');
    script.id = "script1"
    script.src = src;
    document.body.appendChild(script);
  }

  function translate() {
    var value = 'http://api.fanyi.baidu.com/api/trans/vip/translate?';
    var date = Date.now();
    var str = '20170605000052254'+text.value+date+'63r1c42X7_buc4OrXm1g';
    var md5 = MD5(str);
    var data = 'q=' + text.value + '&from=auto&to=' + lang + '&appid=20170605000052254' + '&salt=' + date + '&sign=' + md5 + "&callback=fn";
    var src = value + data;
    createScript(src);
  }

  function init() {

    title.onclick = langShow;

    for (var i = 0; i < length; i++) {
      lis[i].onclick = changeLang;
    }

    reset.onclick = function() {
      text.value = "";
    }

    trans.onclick = function() {
      if (text.value == "") {
        return;
      }
      var script = document.querySelector('#script1');
      if (script) {
        script.parentNode.removeChild(script);
        translate();
      } else {
        translate();
      } 
    }

    text.onkeydown = function() {
      clearTimeout(timer);
      timer = setInterval(function() {
        if (text.value == "") {
          return;
        }
        var script = document.querySelector('#script1');
        if (script) {
          script.parentNode.removeChild(script);
          translate();
        } else {
          translate();
        } 
      }, 500);
      clearTimeout(timer);
    }
  }
  init(); 
})();
function fn(str) {
  var result = document.querySelector(".right .cont");
  result.innerHTML = str.trans_result[0].dst;
}

以上就是实现翻译的过程，效果图：

中 - 英

中 - 韩

这样一个小小的翻译小Demo就完成了，主要还是练习原生js，理解跨域请求的原理，其实跨域请求的方法很多，比如<img>标签的src，<iframe>等等。这些方法大家都得去一一了解。

本文分享到此结束，笔者技术有限，理解有误的地方还请大家多提，大家可以共同学习。

标签
js代码
语言翻译
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