Add some usage examples to the readme

README.md

@@ -8,8 +8,47 @@ V8 version: 7.6.303.31
 import "rogchap.com/v8go"
 ```
 
-## V8 Dependancy
+### Running a script
+
+```go
+ctx, _ := v8go.NewContext(nil) // creates a new V8 context with a new Isolate aka VM
+ctx.RunScript("const add = (a, b) => a + b", "math.js") // executes a script on the global context
+ctx.RunScript("const result = add(3, 4)", "main.js") // any functions previously added to the context can be called
+val, _ ctx.RunScript("result", "value.js") // return a value in JavaScript back to Go
+fmt.Printf("addition result: %s", val)
+```
+
+### One VM, many contexts
+
+```go
+vm, _ := v8go.NewIsolate() // creates a new JavaScript VM
+ctx1, _ := v8go.NewContext(vm) // new context within the VM
+ctx1.RunScript("const multiply = (a, b) => a * b", "math.js")
+
+ctx2, _ := v8go.NewContext(vm) // another context on the same VM
+if _, err := ctx2.RunScript("multiply(3, 4)", "main.js"); err != nil {
+  // this will error as multiply is not defined in this context
+}
+```
+
+### Javascript errors
+
+```go
+val, err := ctx.RunScript(src, filename)
+if err != nil {
+  err = err.(v8go.JSError) // JavaScript errors will be returned as the JSError struct
+  fmt.Println(err.Message) // the message of the exception thrown
+  fmt.Println(err.Location) // the filename, line number and the column where the error occured
+  fmt.Println(err.StackTrace) // the full stack trace of the error, if available
+
+  fmt.Printf("javascript error: %v", err) // will format the standard error message
+  fmt.Printf("javascript stack trace: %+v", err) // will format the full error stack trace
+}
+```
+
+
+## V8 dependancy
 In order to make `v8go` usable as a standard Go package, prebuilt static libraries of V8
-are included for Linux and OSX ie. you should not require to build V8 yourself.
+are included for Linux and OSX ie. you *should not* require to build V8 yourself.
 
 V8 requires 64-bit, therfore will not work on 32-bit systems. 

context_test.go

@@ -9,7 +9,7 @@ import (
 func TestContextExec(t *testing.T) {
 	t.Parallel()
 	ctx, _ := v8go.NewContext(nil)
-	ctx.RunScript(`function add(a, b) { return a + b }`, "add.js")
+	ctx.RunScript(`const add = (a, b) => a + b`, "add.js")
 	val, _ := ctx.RunScript(`add(3, 4)`, "main.js")
 	rtn := val.String()
 	if rtn != "7" {