How to revert from step 3 to step 1? I read a lot and used google before asking. Here is my listing with comments: // --- STEP 1 --- x1=getFile('filename'); // I get raw 16 bit binary string (it is not just a text) // --- STEP 2 --- x2=x1.split('').map(function(x){return x.charCodeAt(0);}); // I convert string to array with ASCII codes (some of them are above 255) // first four elements of this array: 63367 63457 95 22 // --- STEP 3 --- x3=new Uint8Array(x2); // I convert ASCII codes to 8 bit data array // first four elements of this array: 135 225 95 22 // --- STEP 4 (PROBLEM) --- // - OPTION A (WORKING) - // if I save x4 to binary file, and then read it (like in STEP 1) // then data is the same as in original // this means that load file 1, do STEP 2, do STEP 3, save as file 2, // load file 2 will result in file 1 has exactly the same // bytes as file 2 (compared in Total Commander) // - OPTION B (PROBLEM) - // problem is how to convert this Uint8Array (from STEP 3) // back to 16 bit ASCII codes array (like STEP 2), // or just to correct JavaScript string // (like it was in STEP 1 before you started to convert it to arrays) // to make this question more simple: // how to revert from step 3 to step 1 Code (markup):