在 if 语句 CasperJS 之后执行操作

Question

我在连续检查页面的属性更改时遇到问题，但我做到了。现在我的主要代码如下所示：

casper.thenOpen('pageurl', function() { 
    this.then(function () {
        function checkReload()
        {
            var cur = this.getElementAttribute("classname", "attr");
            if (cur == "target") {here
                return; // finished
            }
            else
            {
                this.echo(cur);
            }
            this.reload();
            this.wait(1, checkReload); // check again in a second
        }
        this.then(checkReload);         
    }).thenEvaluate(function(){
        this.click("#new_add");
        this.echo("done567");   
        this.then.waitForSelector(".cartGdList",
            function pass () {
                this.click("...");
                this.echo("done8");
                this.then(function () {
                    this.waitForSelector(".cart_s_Box",
                        function pass () {
                            this.click("#js_upFormBtn");
                            this.echo("step4");
                            var end = new Date().getTime();
                            var time = end - start;
                            this.echo('time: ' + time + 'ms*');
                        },
                        function fail () {
                            this.echo('fail');
                        }
                    );
                });
            },
            function fail () {
                this.echo('fail');
            }
        );
    });
});

在 if 语句之后就可以了 if(cur == "target") 我想执行这段代码：

this.click("#new_add");
this.echo("done567");   
this.then.waitForSelector(".cartGdList",
    function pass () {
        this.click("...");
        this.echo("done8");
        this.then(function () {
            this.waitForSelector(".cart_s_Box",
                function pass () {
                    this.click("#js_upFormBtn");
                    this.echo("step4");
                    var end = new Date().getTime();
                    var time = end - start;
                    this.echo('time: ' + time + 'ms*');
                },
                function fail () {
                    this.echo('fail');
                }
            );
        });
    },
    function fail () {
        this.echo('fail');
    }
);

我该怎么做，我试着把它放在 thenEvaluate 上，但这不起作用。

Answer 1

你有很多不必要的嵌套，但最重要的是。你想在 if 分支中执行一些代码。好的，然后将代码放在 if-branch.

casper.thenOpen('pageurl', function() { 
    this.then(function () {
        function checkReload()
        {
            var cur = this.getElementAttribute("classname", "attr");
            if (cur == "target") {
                this.click("#new_add");
                this.echo("done567");
                // ...
                return; // stop recursion
            }
            else
            {
                this.echo(cur);
            }
            this.reload();
            this.wait(1, checkReload); // check again in a second
        }
        this.then(checkReload);
        // ...

如果不想缩进太多，也可以把代码放在一个函数里。

function myIfBranch(){
    this.click("#new_add");
    this.echo("done567");
    // ...
}

casper.thenOpen('pageurl', function() { 
    this.then(function () {
        function checkReload()
        {
            var cur = this.getElementAttribute("classname", "attr");
            if (cur == "target") {
                myIfBranch.call(this);
                return; // stop recursion
            }
            else
            {
                this.echo(cur);
            }
            this.reload();
            this.wait(1, checkReload); // check again in a second
        }
        this.then(checkReload);
        // ...

至于不必要的嵌套。请记住，then* 和 wait* 函数实际上都是异步步骤函数，并且都以相同的异步方式运行。这是一个清理过的例子：

function myIfBranch(){
    this.click("#new_add");
    this.echo("done567");   
    this.waitForSelector(".cartGdList",
        function pass () {
            this.click("...");
            this.echo("done8");
            this.waitForSelector(".cart_s_Box",
                function pass () {
                    this.click("#js_upFormBtn");
                    this.echo("step4");
                    var end = new Date().getTime();
                    var time = end - start;
                    this.echo('time: ' + time + 'ms*');
                },
                function fail () {
                    this.echo('fail');
                }
            );
        },
        function fail () {
            this.echo('fail');
        }
    );
}

casper.thenOpen('pageurl', function() {
    function checkReload() {
        var cur = this.getElementAttribute("classname", "attr");
        if (cur == "target") {
            myIfBranch.call(this);
            return; // finished
        }
        else
        {
            this.echo(cur);
        }
        this.reload();
        this.wait(1, checkReload); // check again in a second
    }
    this.then(checkReload);

请记住 casper.evaluate 和 casper.thenEvaluate 中的 this 不是指 casper，而是指 window。根本就没有 window.click、window.echo 或 window.then 函数。另外，this.then.waitForSelector(...) 没有意义。

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