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| 1 | +## 24-Create-Node-JS-Command-Line-Tools |
| 2 | + |
| 3 | +**folder 01** |
| 4 | + |
| 5 | +## 1. 03 Working with Modules |
| 6 | + |
| 7 | +## 2. 04 Invisible Node Functions |
| 8 | + |
| 9 | +```javascript |
| 10 | +// in index.js |
| 11 | +console.log(arguments) |
| 12 | +``` |
| 13 | + |
| 14 | +This prints out the arguments huge object to the console |
| 15 | + |
| 16 | +```json |
| 17 | +[Arguments] { |
| 18 | + ... |
| 19 | +} |
| 20 | +``` |
| 21 | + |
| 22 | +```javascript |
| 23 | +// in index.js |
| 24 | +console.log(arguments) |
| 25 | +console.log(require) |
| 26 | +console.log(module) |
| 27 | +console.log(__filename) |
| 28 | +console.log(__dirname) |
| 29 | +``` |
| 30 | + |
| 31 | +## 3. 05 The Require Cache |
| 32 | + |
| 33 | +```javascript |
| 34 | +// in index.js |
| 35 | +require('./myscript.js') |
| 36 | +console.log(require.cache) |
| 37 | + |
| 38 | +// in myscript.js |
| 39 | +const message = 'hello world' |
| 40 | + |
| 41 | +module.exports = message |
| 42 | +``` |
| 43 | + |
| 44 | +## 4. 06 Files Get Required Once |
| 45 | + |
| 46 | +```javascript |
| 47 | +// in index.js |
| 48 | +const counterObject = require('./myscript.js') |
| 49 | + |
| 50 | +console.log(counterObject.getCounter()) |
| 51 | +counterObject.incrementCounter() |
| 52 | +console.table(counterObject.getCounter()) |
| 53 | + |
| 54 | +const newCounterObject = require('./myscript.js') |
| 55 | +console.log(newCounterObject.getCounter()) |
| 56 | + |
| 57 | +// in myscript.js |
| 58 | +let counter = 0 |
| 59 | + |
| 60 | +module.exports = { |
| 61 | + incrementCounter() { |
| 62 | + counter = counter + 1 |
| 63 | + }, |
| 64 | + getCounter() { |
| 65 | + return counter |
| 66 | + }, |
| 67 | +} |
| 68 | +``` |
| 69 | + |
| 70 | +## 5. 07 Debugging with Node |
| 71 | + |
| 72 | +`node inspect index.js` |
| 73 | + |
| 74 | +#### CLI Debugger Commands |
| 75 | + |
| 76 | +- c => Continue execution until program ends or next debugger statement |
| 77 | +- n => Run the next line of code |
| 78 | +- s => Step in to a function |
| 79 | +- o => Step out of the current function |
| 80 | + |
| 81 | +**After entering the debu> we can open the repl console by typing repl in the debugger** |
| 82 | + |
| 83 | +`node inspect index.js` => Start up a debugger **CLI** and pause execution whenever a 'debugger' statement is hit |
| 84 | + |
| 85 | +`node --inspect index.js` => Start up a debugger instance and pause execution whenever a 'debugger' statement is hit. Access the debugger at '**chrome://inspect'** |
| 86 | + |
| 87 | +`node --inspect-brk index.js` => Start up a debugger instance and wait to execute until a debugger is connected. Access the debugger at '**chrome://inspect'** |
| 88 | + |
| 89 | +## 6. 09 Accessing Standard Library Modules |
| 90 | + |
| 91 | +**folder 01** |
| 92 | + |
| 93 | +NodeJS documentation https://nodejs.org/ |
| 94 | + |
| 95 | +https://nodejs.org/dist/latest-v18.x/docs/api/fs.html |
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