js中怎么把arrayBuffer轉換成字符串

最近做websocket的測試，需要將收到的數據轉換成字符串，在網上找了好幾個方法都不好使。同事給了一個函數，測試好用。寫筆記記錄一下。

funtion ArrayBufferUTF8ToStr(array) {
        var out,i,len,c;
        var char2,char3;
        if (array instanceof ArrayBuffer) {
            array = new Uint8Array(array);
        }
    
        out = "";
        len = array.length;
        i = 0;
        while(i < len) {
            c = array[i++];
            switch(c >> 4) {
                case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:
                    // 0xxxxxxx
                    out += String.fromCharCode(c);
                    break;
                case 12: case 13:
                    // 110x xxxx   10xx xxxx
                    char2 = array[i++];
                    out += String.fromCharCode(((c & 0x1F) << 6) | (char2 & 0x3F));
                    break;
                case 14:
                    // 1110 xxxx  10xx xxxx  10xx xxxx
                    char2 = array[i++];
                    char3 = array[i++];
                    out += String.fromCharCode(((c & 0x0F) << 12) |
                        ((char2 & 0x3F) << 6) |
                        ((char3 & 0x3F) << 0));
                    break;
            }
        }
    
        return out;
    }