为什么React Native运算符在调试和发布版本上表现不同

Question

Does anyone know why operators behave differently on react native (0.54.2) debug and release builds?

This works perfectly on debug. If usageTip is something else than empty string and we are loading first time, we enter inside if and show user the usageTip:

if (this.props.usageTip =! '' && this.props.firstTimeLoading) {
    return (
        <Text style={styles.disclaimerTextStyle}>{this.props.usageTip}</Text>
    );
}

But on release the if line will somehow set imageTip to boolean value true. What is happening there?

I found a way to get it working on release also:

if (this.props.firstTimeLoading && (this.props.usageTip ==! '')) {
        return (
            <Text style={styles.disclaimerTextStyle}>{this.props.usageTip}</Text>
        );
    }

But I am very confused why the first version of my code behaved like that? It was also very hard to find the problem because release build debugging is not very easy. (At least I don't know any easy way)

Answer 1

When using React Native, you're going to be running your JavaScript code in two environments:

• In most cases, React Native will use JavaScriptCore, the JavaScript engine that powers Safari.

• When using Chrome debugging, all JavaScript code runs within Chrome itself, communicating with native code via WebSockets. Chrome uses V8 as its JavaScript engine.

While both environments are very similar, you may end up hitting some inconsistencies. To get More Detail