背景：有个蓝牙相关的小程序项目，需要向蓝牙设备写入数据，用到相关的知识，记录一下。

一、字符串转16进制字符串

    // 字符串转16进制字符串
    string2Hex(str) {
      let val = ""
      for (let i = 0; i < str.length; i++) {
        if (val == "")
          val = str.charCodeAt(i).toString(16)
        else
          val += str.charCodeAt(i).toString(16)
      }
      return val
    }

二、16进制字符串转ArrayBuffer

    // 16进制字符串转ArrayBuffer
    hex2ArrayBuffer(hex_str) {
      // let hex_str = 'AA5504B10000B5'
      let typedArray = new Uint8Array(hex_str.match(/[\da-f]{2}/gi).map(function (h) {
        return parseInt(h, 16)
      }))
      let buffer = typedArray.buffer
      return buffer
    }

三、ArrayBuffer转16进制字符串

    // ArrayBuffer转16进制字符串
    arrayBuffer2Hex(buffer) {
      const hexArr = Array.prototype.map.call(
        new Uint8Array(buffer),
        function (bit) {
          return ('00' + bit.toString(16)).slice(-2)
        }
      )
      return hexArr.join('')
    }

四、16进制字符串转字符串

    // 16进制字符串转字符串
    hex2String(hex_str) {
      let trimedStr = hex_str.trim();
      let rawStr = trimedStr.substr(0,2).toLowerCase() === "0x" ? trimedStr.substr(2) : trimedStr;
      let len = rawStr.length;
      if(len % 2 !== 0) {
        console.log("Illegal Format ASCII Code!");
        return "";
      }
      let curCharCode;
      let resultStr = [];
      for(let i = 0; i < len;i = i + 2) {
        curCharCode = parseInt(rawStr.substr(i, 2), 16); // ASCII Code Value
        resultStr.push(String.fromCharCode(curCharCode));
      }
      return resultStr.join("");
    }

五、字符串转ArrayBuffer

    // 字符串转ArrayBuffer
    string2ArrayBuffer(str) {
      // 首先将字符串转为16进制
      let val = ""
      for (let i = 0; i < str.length; i++) {
        if (val === '') {
          val = str.charCodeAt(i).toString(16)
        } else {
          val += ',' + str.charCodeAt(i).toString(16)
        }
      }
      // 将16进制转化为ArrayBuffer
      return new Uint8Array(val.match(/[\da-f]{2}/gi).map(function (h) {
        return parseInt(h, 16)
      })).buffer
    }

六、ArrayBuffer转字符串

    // ArrayBuffer转字符串
    arrayBuffer2String(buffer) {
      return String.fromCharCode.apply(null, new Uint8Array(buffer))
    }

记录于2022-01-05.