turn into promises

Signed-off-by: Arnav Gupta <[email protected]>

Author: championswimmer

Lecture11/promises/callbacks.js

@@ -0,0 +1,43 @@
+function readFile1(path, done) {
+  if (typeof path !== 'string' || path.length < 3) {
+    done(new Error('Path invalid'))
+  }
+  setTimeout(() => {
+    done(null, 'Sample data 1')
+  }, 1000)
+}
+
+function readFile2(path, done) {
+  if (typeof path !== 'string' || path.length < 3) {
+    done(new Error('Path invalid'))
+  }
+  setTimeout(() => {
+    done(null, 'Sample data 2')
+  }, 2000)
+}
+
+function readFile3(path, done) {
+  if (typeof path !== 'string' || path.length < 3) {
+    done(new Error('Path invalid'))
+  }
+  setTimeout(() => {
+    done(null, 'Sample data 3')
+  }, 3000)
+}
+
+function writeFile(data1, data2, data3, done) {
+  setTimeout(() => {
+    console.log('data written', [data1, data2, data3])
+    done(null)
+  }, 2000)
+}
+
+readFile1('asdsad', (err, data1) => {
+  readFile2('dnbdfgn', (err, data2) => {
+    readFile3('dgngdn', (err, data3) => {
+      writeFile(data1, data2, data3, () => {
+
+      })
+    })
+  })
+})

Lecture11/promises/promises.js

@@ -0,0 +1,67 @@
+function readFile1(path) {
+  return new Promise((resolve, reject) => {
+    if (typeof path !== 'string' || path.length < 3) {
+      reject(new Error('Path invalid'))
+    }
+    setTimeout(() => {
+      resolve('Sample data 1')
+    }, 1000)
+  })
+}
+
+function readFile2(path) {
+  return new Promise((resolve, reject) => {
+    if (typeof path !== 'string' || path.length < 3) {
+      reject(new Error('Path invalid'))
+    }
+    setTimeout(() => {
+      resolve('Sample data 2')
+    }, 2000)
+  })
+}
+
+function readFile3(path) {
+  return new Promise((resolve, reject) => {
+    if (typeof path !== 'string' || path.length < 3) {
+      reject(new Error('Path invalid'))
+    }
+    setTimeout(() => {
+      resolve('Sample data 3')
+    }, 3000)
+  })
+}
+
+function writeFile(data1, data2, data3, done) {
+  return new Promise((resolve, reject) => {
+    setTimeout(() => {
+      console.log('data written', [data1, data2, data3])
+      resolve()
+    }, 2000)
+  })
+}
+
+readFile1('asdsad', (err, data1) => {
+  readFile2('dnbdfgn', (err, data2) => {
+    readFile3('dgngdn', (err, data3) => {
+      writeFile(data1, data2, data3, () => {})
+    })
+  })
+})
+
+let errH = (err) => {
+  if (err) console.error(err)
+}
+
+readFile1('asdasd')
+  .then((data1) => {
+    readFile2('')
+      .then((data2) => {
+        readFile3('dgngdn')
+          .then((data3) => {
+            writeFile(data1, data2, data3)
+          })
+          .catch(errH)
+      })
+      .catch(errH)
+  })
+  .catch(errH)