javascript - 如何在后续调用中重用在 casperJS 调用中填充的变量？

Question

我在 CasperJS 脚本中遇到以下范围问题。传递给 casper.thenOpenAndEvaluate() 时，baseTargetUrl 未定义。为什么会这样，我该如何解决？

var baseTargetUrl;
        .....
casper.then(function() {
    baseTargetUrl = this.evaluate(function() {
        return __utils__.getElementByXPath('//*[@id="wrapper"]/div[1]/a[2]')["href"];
    });
    console.log('logging: '+baseTargetUrl); // works
});

casper.thenOpenAndEvaluate(baseTargetUrl ,function() { //baseTargetUrl is undefined here
    var test = document.querySelector('myselector');
    //do other stuff

});

Answer 1

如您所知，我们无法从外部异步调用中获取变量。这看起来有点老套，但这是我目前所拥有的最好的....

var baseTargetUrl;
        .....
casper.then(function() {
    baseTargetUrl = this.evaluate(function() {
        return __utils__.getElementByXPath('//*[@id="wrapper"]/div[1]/a[2]')["href"];
    });
    console.log('logging: '+baseTargetUrl); // works

    this.thenOpenAndEvaluate(baseTargetUrl ,function() { // 'this' being the instance of casper
        var test = document.querySelector('myselector');
        //do other stuff

    });
});