chromedp/eval.go
Kenneth Shaw b57afce7e7 Fixing Evaluate and EvaluateAsDevTools actions
- Update Evaluate action to also work with []byte
- Update Evaluate documentation
- Fix EvaluateAsDevTools action
- Refactor Query actions to use EvaluateAsDevTools
2017-02-08 15:18:55 +07:00

109 lines
3.1 KiB
Go

package chromedp
import (
"context"
"encoding/json"
"github.com/knq/chromedp/cdp"
rundom "github.com/knq/chromedp/cdp/runtime"
)
// Evaluate evaluates the Javascript expression, unmarshaling the result of the
// script evaluation to res.
//
// If res is *[]byte, then the result of the script evaluation will be returned
// "by value" (ie, JSON-encoded) and res will be set to the raw value.
//
// Alternatively, if res is **chromedp/cdp/runtime.RemoteObject, then it will
// be set to the returned RemoteObject and no attempt will be made to convert
// the value to an equivalent Go type.
//
// Otherwise, if res is any other Go type, the result of the script evaluation
// will be returned "by value" (ie, JSON-encoded), and subsequently will be
// json.Unmarshal'd into res.
//
// Note: any exception encountered will be returned as an error.
func Evaluate(expression string, res interface{}, opts ...EvaluateOption) Action {
if res == nil {
panic("res cannot be nil")
}
return ActionFunc(func(ctxt context.Context, h cdp.FrameHandler) error {
var err error
// set up parameters
p := rundom.Evaluate(expression)
switch res.(type) {
case **rundom.RemoteObject:
default:
p = p.WithReturnByValue(true)
}
// apply opts
for _, o := range opts {
p = o(p)
}
// evaluate
v, exp, err := p.Do(ctxt, h)
if err != nil {
return err
}
if exp != nil {
return exp
}
switch x := res.(type) {
case **rundom.RemoteObject:
*x = v
return nil
case *[]byte:
*x = []byte(v.Value)
return nil
}
// unmarshal
return json.Unmarshal(v.Value, res)
})
}
// EvaluateAsDevTools is an action that evaluates a Javascript expression in
// the same context as Chrome DevTools would, exposing the Command Line API to
// the script evaluating the expression in the "console" context.
//
// Note: this should not be used with any untrusted code.
func EvaluateAsDevTools(expression string, res interface{}, opts ...EvaluateOption) Action {
return Evaluate(expression, res, append(opts, EvalObjectGroup("console"), EvalWithCommandLineAPI)...)
}
// EvaluateOption is an Evaluate call option.
type EvaluateOption func(*rundom.EvaluateParams) *rundom.EvaluateParams
// EvalObjectGroup is a evaluate option to set the object group.
func EvalObjectGroup(objectGroup string) EvaluateOption {
return func(p *rundom.EvaluateParams) *rundom.EvaluateParams {
return p.WithObjectGroup(objectGroup)
}
}
// EvalWithCommandLineAPI is an evaluate option to make the DevTools Command
// Line API available to the evaluated script.
//
// Note: this should not be used with any untrusted code.
func EvalWithCommandLineAPI(p *rundom.EvaluateParams) *rundom.EvaluateParams {
return p.WithIncludeCommandLineAPI(true)
}
// EvalSilent is a evaluate option that will cause script evaluation to ignore
// exceptions.
func EvalSilent(p *rundom.EvaluateParams) *rundom.EvaluateParams {
return p.WithSilent(true)
}
// EvalAsValue is a evaluate option that will case the script to encode its
// result as a value.
func EvalAsValue(p *rundom.EvaluateParams) *rundom.EvaluateParams {
return p.WithReturnByValue(true)
}