Add error handling examples

Author: tshemsedinov

.eslintrc.yml

@@ -0,0 +1,173 @@
+env:
+  es6: true
+  node: true
+extends: 'eslint:recommended'
+globals:
+  api: false
+rules:
+  indent:
+    - error
+    - 2
+    - SwitchCase: 1
+      VariableDeclarator:
+        var: 2
+        let: 2
+        const: 3
+      MemberExpression: 1
+  linebreak-style:
+    - error
+    - unix
+  quotes:
+    - error
+    - single
+  semi:
+    - error
+    - always
+  eqeqeq:
+    - error
+    - always
+  no-loop-func:
+    - error
+  strict:
+    - error
+    - global
+  block-spacing:
+    - error
+    - always
+  brace-style:
+    - error
+    - 1tbs
+    - allowSingleLine: true
+  camelcase:
+    - error
+  comma-style:
+    - error
+    - last
+  comma-spacing:
+    - error
+    - before: false
+      after: true
+  eol-last:
+    - error
+  func-call-spacing:
+    - error
+    - never
+  key-spacing:
+    - error
+    - beforeColon: false
+      afterColon: true
+      mode: minimum
+  keyword-spacing:
+    - error
+    - before: true
+      after: true
+      overrides:
+        function:
+          after: false
+  max-len:
+    - error
+    - code: 80
+      ignoreUrls: true
+  max-nested-callbacks:
+    - error
+    - max: 7
+  new-cap:
+    - error
+    - newIsCap: true
+      capIsNew: true
+      properties: true
+  new-parens:
+    - error
+  no-lonely-if:
+    - error
+  no-trailing-spaces:
+    - error
+  no-unneeded-ternary:
+    - error
+  no-whitespace-before-property:
+    - error
+  object-curly-spacing:
+    - error
+    - always
+  operator-assignment:
+    - error
+    - always
+  operator-linebreak:
+    - error
+    - after
+  semi-spacing:
+    - error
+    - before: false
+      after: true
+  space-before-blocks:
+    - error
+    - always
+  space-before-function-paren:
+    - error
+    - never
+  space-in-parens:
+    - error
+    - never
+  space-infix-ops:
+    - error
+  space-unary-ops:
+    - error
+    - words: true
+      nonwords: false
+      overrides:
+        typeof: false
+  no-unreachable:
+    - error
+  no-global-assign:
+    - error
+  no-self-compare:
+    - error
+  no-unmodified-loop-condition:
+    - error
+  no-constant-condition:
+    - error
+    - checkLoops: false
+  no-console:
+    - off
+  no-useless-concat:
+    - error
+  no-useless-escape:
+    - error
+  no-shadow-restricted-names:
+    - error
+  no-use-before-define:
+    - error
+    - functions: false
+  arrow-body-style:
+    - error
+    - as-needed
+  arrow-spacing:
+    - error
+  no-confusing-arrow:
+    - error
+    - allowParens: true
+  no-useless-computed-key:
+    - error
+  no-useless-rename:
+    - error
+  no-var:
+    - error
+  object-shorthand:
+    - error
+    - always
+  prefer-arrow-callback:
+    - error
+  prefer-const:
+    - error
+  prefer-numeric-literals:
+    - error
+  prefer-rest-params:
+    - error
+  prefer-spread:
+    - error
+  rest-spread-spacing:
+    - error
+    - never
+  template-curly-spacing:
+    - error
+    - never

.gitignore

@@ -0,0 +1,3 @@
+node_modules
+*.log
+.DS_Store

JavaScript/1-sync-try.js

@@ -0,0 +1,21 @@
+'use strict';
+
+function sum(a, b) {
+  if (typeof(a) === 'number' && typeof(b) === 'number') {
+    return a + b;
+  } else {
+    throw new Error('a and b should be numbers');
+  }
+}
+
+try {
+  console.log(sum(2, 3));
+} catch (e) {
+  console.log(e.message);
+}
+
+try {
+  console.log(sum(7, 'A'));
+} catch (e) {
+  console.log(e.message);
+}

JavaScript/2-sync-tuple.js

@@ -0,0 +1,12 @@
+'use strict';
+
+function fn(a, b) {
+  if (typeof(a) === 'number' && typeof(b) === 'number') {
+    return [null, a + b];
+  } else {
+    return [new Error('a and b should be numbers')];
+  }
+}
+
+console.log(fn(2, 3));
+console.log(fn(7, 'A'));

JavaScript/3-async.js

@@ -0,0 +1,25 @@
+'use strict';
+
+function fn2(a, b, callback) {
+  if (typeof(a) === 'number' && typeof(b) === 'number') {
+    callback(null, a + b);
+  } else {
+    callback(new Error('a and b should be numbers'));
+  }
+}
+
+fn2(2, 3, (err, result) => {
+  if (err) {
+    console.log(err.message);
+    return;
+  }
+  console.log(result);
+});
+
+fn2(7, 'A', (err, result) => {
+  if (err) {
+    console.log(err.message);
+    return;
+  }
+  console.log(result);
+});

JavaScript/4-process.js

@@ -0,0 +1,16 @@
+'use strict';
+
+process.on('uncaughtException', (e) => {
+  console.log('on uncaughtException: ' + e.message);
+});
+
+function sum(a, b) {
+  if (typeof(a) === 'number' && typeof(b) === 'number') {
+    return a + b;
+  } else {
+    throw new Error('a and b should be numbers');
+  }
+}
+
+console.log(sum(2, 3));
+console.log(sum(7, 'A'));