How to convert float into byte array?

Question

I want to convert a float value like 26,4 into a byte array. Something like: [51,51,-45,65]. Another example: 32,2 > [-51, -52, 0, 66].

I can do it in Arduino C++ and Python, but I don't see how to do it in JavaScript.

I have an input field in my HTML page where I want to write my float value and decode it before sending it to a Python script.

Is it possible?

possible duplicate of Convert "float" to bytes in Javascript without Float32Array — Scott Sauyet
– Scott Sauyet, Commented Apr 14, 2015 at 14:31
@ScottSauyet: Why without typed arrays? They make it so much simpler… — Bergi
– Bergi, Commented Apr 14, 2015 at 15:37
You're right. This is not a duplicate of that one. Yes, the typed arrays are clearly easier. Retracted my close vote. — Scott Sauyet
– Scott Sauyet, Commented Apr 14, 2015 at 15:44
@Bergi Typed arrays are only for ES6. Older versions don't have them. But yes, the questions are related and complementary but not dupes — DarkCygnus
– DarkCygnus, Commented Oct 29, 2019 at 18:38

user1693593 · Accepted Answer · 2015-04-14 15:30:22Z

Typed Arrays

First create a Float32Array which is a view on top of an actual byte-buffer (ArrayBuffer). We can allocate the buffer and view in a single operation:

var farr = new Float32Array(2);  // two indexes each 4 bytes

Store the floating point numbers. These will be stored in IEEE-754 format:

farr[0] = 26.4;
farr[1] = 32.2;

Now we can add another view for the underlying buffer, this time signed 8-bit view:

var barr = new Int8Array(farr.buffer);   // use the buffer of Float32Array view

console.log(barr);
// -> 51,51,-45,65,-51,-52,0,66

Live demo below

var farr = new Float32Array(2);  // two indexes each 4 bytes
farr[0] = 26.4;
farr[1] = 32.2;

var barr = new Int8Array(farr.buffer);   // use the buffer of Float32Array view
console.log(barr);

document.querySelector("div").innerHTML =  barr[0]+","+barr[1]+","+barr[2]+","+barr[3]+","+barr[4]+","+barr[5]+","+barr[6]+","+barr[7];

<div></div>

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How to convert float into byte array?

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Typed Arrays

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