Fixed Issue241: add try and catch

JavaScript_Basics/try_and_catch.js

@@ -0,0 +1,71 @@
+//Try and Catch
+
+/* In JavaScript,  try/catch/finally** statement handle errors that may occur in the block.
+
+try statement eables you to test your code in the block.
+catch statement enables you to execute a block of code when it catches an error.
+finally statement enables you to execute always after try and catch, regardless of an exception was thrown or caught.
+*/
+
+
+// Syntax
+
+try { 
+    throw 'exception'; // generate an exception
+} catch (error) {
+    // statements to handle any exceptions
+} finally {
+    // always runs regardless of the resulf ot try/catch
+}
+
+
+// Errors
+
+// Reference Error
+
+try {
+    hello(); // hello is not defined so it will cause a reference errorr
+} catch (error) {
+    console.log(error);
+} finally {
+    console.log('Finally runs reguardess of the reuslt');
+}
+
+
+// Type Error
+
+try {
+    null.hello(); // hello is not defined so it will cause a reference errorr
+} catch (error) {
+    console.log("You cannot call from null"); 
+} finally {
+    console.log('Finally runs reguardess of the reuslt');
+}
+
+
+// Syntax Error
+
+try {
+    eval('2+2'); // thsi works fine
+    eval('Hello, World!'); // this will generate error
+} catch (error) {
+    console.log("Syntax error"); 
+} finally {
+    console.log('Finally runs reguardess of the reuslt');
+}
+
+
+// User Defined Error
+
+const person = {name:John, age: 23};
+
+try {
+    if(!person.gender){
+        // throw 'person has no gender'
+        throw new SyntaxError('Person has no gender');
+    }
+} catch (error) {
+    console.log("You cannot call from null"); 
+} finally {
+    console.log('Finally runs reguardess of the reuslt');
+}

docs/JavaScript_Basics/try_and_catch.md

@@ -0,0 +1,70 @@
+# Try and Catch
+
+In JavaScript, **try**/**catch**/**finally** statement handle errors that may occur in the block.
+
+**try** statement eables you to test your code in the block.
+**catch** statement enables you to execute a block of code when it catches an error.
+**finally** statement enables you to execute always after try and catch, regardless of an exception was thrown or caught.
+
+## Syntax
+```js
+try { 
+    throw 'exception'; // generate an exception
+} catch (error) {
+    // statements to handle any exceptions
+} finally {
+    // always runs regardless of the resulf ot try/catch
+}
+```
+
+## Errors
+
+### Reference Error
+```js
+try {
+    hello(); // hello is not defined so it will cause a reference errorr
+} catch (error) {
+    console.log(error);
+} finally {
+    console.log('Finally runs reguardess of the reuslt');
+}
+```
+
+### Type Error
+```js
+try {
+    null.hello(); // hello is not defined so it will cause a reference errorr
+} catch (error) {
+    console.log("You cannot call from null"); 
+} finally {
+    console.log('Finally runs reguardess of the reuslt');
+}
+```
+
+### Syntax Error
+```js
+try {
+    eval('2+2'); // thsi works fine
+    eval('Hello, World!'); // this will generate error
+} catch (error) {
+    console.log("Syntax error"); 
+} finally {
+    console.log('Finally runs reguardess of the reuslt');
+}
+```
+
+### User Defined Error
+```js
+const person = {name:John, age: 23};
+
+try {
+    if(!person.gender){
+        // throw 'person has no gender'
+        throw new SyntaxError('Person has no gender');
+    }
+} catch (error) {
+    console.log("You cannot call from null"); 
+} finally {
+    console.log('Finally runs reguardess of the reuslt');
+}
+```