How to flash Arduino through soft serial?

Yes. I searched on the forum and use these codes:

let rawCodes =[4400,4350,550,1600,600,500,550,1650,550,1600,550,550,550,550,550,1600,550,550,550,550,550,1600,550,550,550,550,550,1600,550,1600,600,500,550,1650,550,550,550,1600,550,1600,600,1600,550,1600,550,550,550,1600,600,1600,550,1600,600,500,550,550,550,550,550,500,600,1600,550,550,550,500,600,1600,550,1600,600,1600,550,550,550,500,600,500,550,550,550,550,550,500,600,500,550,550,550,1600,600,1600,550,1600,550,1650,550,1600,550].map(function(x) {return x/1000;});
analogWrite(NodeMCU.D5, 0.9, {freq:38000});
digitalPulse(NodeMCU.D5, 1, rawCodes);
digitalPulse(NodeMCU.D5, 1, 0);

And it will reboot itself during process.

And I had searched on the web, they said i2s can generate 38khz PWM signal, but I don't know how to write the code in Espruino, so if you know how to do with this, please teach me about it, thank you very much.