Enter the expression in the input box, the interface reports an error, the front end encodes the expression, and decodes it during display.

// 表情编码
			utf16toEntities(str) {
				var patt = /[\ud800-\udbff][\udc00-\udfff]/g;
				// 检测utf16字符正则
				str = str.replace(patt, function(char) {
					var H, L, code;
					if (char.length === 2) {
						H = char.charCodeAt(0);
						// 取出高位
						L = char.charCodeAt(1);
						// 取出低位
						code = (H - 0xD800) * 0x400 + 0x10000 + L - 0xDC00;
						// 转换算法
						return "&#" + code + ";";
					} else {
						return char;
					}
				});
				//    str = str.replace(/&#/g,'^^');
				return str;
			},
			//表情解码
			entitiestoUtf16(str) {
				// 检测出形如〹形式的字符串
				var strObj = this.utf16toEntities(str);
				var patt = /&#\d+;/g;
				var H, L, code;
				var arr = strObj.match(patt) || [];
				for (var i = 0; i < arr.length; i++) {
					code = arr[i];
					code = code.replace('&#', '').replace(';', '');
					// 高位
					H = Math.floor((code - 0x10000) / 0x400) + 0xD800;
					// 低位
					L = (code - 0x10000) % 0x400 + 0xDC00;
					code = "&#" + code + ";";
					var s = String.fromCharCode(H, L);
					strObj = strObj.replace(code, s);
				}
				return strObj;
			},