Node. js asynchronous non-blocking callback function

Callback Function (asynchronous non-blocking) callback function (asynchronous non-blocking)

Main. js File

[Code] // introduce the file module var fs = require ('fs'); // read the test.txtfile fs.readfile('test.txt ', function (err, data) {if (err) return console. log (err); console. log (data. toString () ;}); console. log ('program execution completed ');

Analysis: first execute the program and then read the file

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