requestAnimationFrame returns Unix timestamp instead of elapsed time

Is this a bug report?

Yes

Have you read the Contributing Guidelines?

Yes

Environment

OS: Linux 4.4
Node: 6.9.4
Yarn: Not Found
npm: 3.10.10
Watchman: Not Found

Packages: (wanted => installed) react-native: 0.48.4 => 0.48.4 react: 16.0.0-alpha.12 => 16.0.0-alpha.12

Target Platform: Android 7 (SDK version 25)

Steps to Reproduce

Create a simple React component that invokes requestAnimationFrame once, stores the time parameter in state, and renders the result:

import React from 'react';

import {
    AppRegistry,
    StyleSheet,
    View,
    Text
} from 'react-native';


const styles = StyleSheet.create({
    container: {
        flex: 1,
        justifyContent: 'center',
    },
})

class App extends React.Component {
    constructor() {
        super();

        this.state = {
            time: 0,
        };

        requestAnimationFrame(time => (
            this.setState({
                time,
            })
        ));
    }

    render() {
        const { showProgressBar } = this.state;

        return (
            <View style={styles.container}>
                <Text>{this.state.time}</Text>
            </View>
        );
    }
}

AppRegistry.registerComponent('App', () => App);

Expected Behavior

The time parameter should be the time elapsed since the “page” “loaded” (navigated to current view or activity?) as is the case in Chrome and Firefox (this value should be performance.now(), according to MDN.

Actual Behavior

The time parameter resolves to the current Unix timestamp (i.e. Date.now()).

Reproducible Demo

https://github.com/jamesseanwright/react-native-requestanimationframe-bug

I’d be happy to submit a PR to fix this, but I’m unsure of how this project versions breaking changes. I can work around this issue, but it would be great to achieve parity with the browser API so that I can avoid platform-specific hacks.

Let me know your thoughts.

Cheers, James

[Esemesek]

I’ve send fix to fbjs, but I wonder if it is better to fix it by adding performance polyfill in https://github.com/facebook/react-native/tree/master/Libraries/polyfills

[patrickkempff]

@TakaGoto go ahead. Feel free to open a PR to fix this 😃