知识点---前端处理支持emoji表情

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>前端处理支持emoji表情</title>
</head>

<body>
    <h1>测试</h1>
    <textarea rows="10" cols="40" id="text"></textarea>
    <button type="" id="enbtn">编码</button>
    <button type="" id="debtn">解码</button>

    <h2>结果</h2>
    <div id="dv"></div>
</body>
</html>

<script>
/**
*
*  Base64 encode / decode
*
**/
    var Base64 = {

        // private property
        _keyStr: "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",

        // public method for encoding
        encode: function (input) {
            var output = "";
            var chr1, chr2, chr3, enc1, enc2, enc3, enc4;
            var i = 0;

            input = Base64._utf8_encode(input);

            while (i < input.length) {

                chr1 = input.charCodeAt(i++);
                chr2 = input.charCodeAt(i++);
                chr3 = input.charCodeAt(i++);

                enc1 = chr1 >> 2;
                enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
                enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
                enc4 = chr3 & 63;

                if (isNaN(chr2)) {
                    enc3 = enc4 = 64;
                } else if (isNaN(chr3)) {
                    enc4 = 64;
                }

                output = output +
                    this._keyStr.charAt(enc1) + this._keyStr.charAt(enc2) +
                    this._keyStr.charAt(enc3) + this._keyStr.charAt(enc4);

            }

            return output;
        },

        // public method for decoding
        decode: function (input) {
            var output = "";
            var chr1, chr2, chr3;
            var enc1, enc2, enc3, enc4;
            var i = 0;

            input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");

            while (i < input.length) {

                enc1 = this._keyStr.indexOf(input.charAt(i++));
                enc2 = this._keyStr.indexOf(input.charAt(i++));
                enc3 = this._keyStr.indexOf(input.charAt(i++));
                enc4 = this._keyStr.indexOf(input.charAt(i++));

                chr1 = (enc1 << 2) | (enc2 >> 4);
                chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
                chr3 = ((enc3 & 3) << 6) | enc4;

                output = output + String.fromCharCode(chr1);

                if (enc3 != 64) {
                    output = output + String.fromCharCode(chr2);
                }
                if (enc4 != 64) {
                    output = output + String.fromCharCode(chr3);
                }

            }

            output = Base64._utf8_decode(output);

            return output;

        },

        // private method for UTF-8 encoding
        _utf8_encode: function (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;
        },

        // private method for UTF-8 decoding
        _utf8_decode: function (utftext) {
            var string = "";
            var i = 0;
            var c = c1 = c2 = 0;

            while (i < utftext.length) {

                c = utftext.charCodeAt(i);

                if (c < 128) {
                    string += String.fromCharCode(c);
                    i++;
                }
                else if ((c > 191) && (c < 224)) {
                    c2 = utftext.charCodeAt(i + 1);
                    string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
                    i += 2;
                }
                else {
                    c2 = utftext.charCodeAt(i + 1);
                    c3 = utftext.charCodeAt(i + 2);
                    string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
                    i += 3;
                }

            }

            return string;
        }

    }

    //编码
    document.getElementById('enbtn').onclick = encodeFn;

    function encodeFn() {
        // 获取 value
        var enval = document.getElementById('text').value;

        // 获取 value 中所有表情
        var reg = enval.match(/[\uD83C|\uD83D|\uD83E][\uDC00-\uDFFF][\u200D|\uFE0F]|[\uD83C|\uD83D|\uD83E][\uDC00-\uDFFF]|[0-9|*|#]\uFE0F\u20E3|[0-9|#]\u20E3|[\u203C-\u3299]\uFE0F\u200D|[\u203C-\u3299]\uFE0F|[\u2122-\u2B55]|\u303D|[\A9|\AE]\u3030|\uA9|\uAE|\u3030/ig);
        console.log(reg)

        // 将所有表情转成 base 64
        var emojiBaseArr = reg.map(function (v) {
            return '[' + Base64.encode(v) + ']'
        })
        console.log(emojiBaseArr);

        // 替换文本中所有表情
        for (var i = 0; i < emojiBaseArr.length; i++) {

            // 相当于每次替换字符串中的第一个
            var str = enval.replace(/[\uD83C|\uD83D|\uD83E][\uDC00-\uDFFF][\u200D|\uFE0F]|[\uD83C|\uD83D|\uD83E][\uDC00-\uDFFF]|[0-9|*|#]\uFE0F\u20E3|[0-9|#]\u20E3|[\u203C-\u3299]\uFE0F\u200D|[\u203C-\u3299]\uFE0F|[\u2122-\u2B55]|\u303D|[\A9|\AE]\u3030|\uA9|\uAE|\u3030/, emojiBaseArr[i]);

            // 将替换后的值重新赋值给 enval
            enval = str;
        }
        console.log(enval);

        return enval;
    }

    //解码
    document.getElementById('debtn').onclick = function () {

        // 前端做了处理  后端不需要做任何操作，只需要原封不动的返回来即可 （ 假设获取后台返回的值 ）
        var deval = encodeFn()
        console.log(deval);

        // 正则获取所有中括号中长度为8位的字符（包括中括号）
        var res = deval.match(/\[[0-9a-zA-Z]{8}\]|\[[0-9a-zA-Z\+]{8}|\[[0-9a-zA-Z\+\/]{8}/g);
        console.log(res);

        // 数组中的元素两边的中括号去掉，得到新的数组
        var arr = res.map(function (v) {
            return v.substr(1, 8)
        })
        console.log(arr);

        // 将新数组中的每个元素解码，得到新的数组
        var deArr = arr.map(function (v) {
            return Base64.decode(v);
        })
        console.log(deArr);

        // 将解码后的元素和文本中正则匹配到的一一替换
        for (var i = 0; i < deArr.length; i++) {
            var decode = deval.replace(/\[[0-9a-zA-Z]{8}\]|\[[0-9a-zA-Z\+]{8}\]|\[[0-9a-zA-Z\+\/]{8}/, deArr[i]);
            deval = decode;
        }
        console.log(deval);

        // 渲染
        document.getElementById('dv').innerHTML = deval
    }

</script>