CasperJS posting only the last item multiple times from my for-loop

问题

CasperJS is awesome but it's not posting to my localhost what my console output is.

casper.wait(5000, function () {
    casper.wait(1000, function () {
        casper.then(function(){
            for  (var i = 0 ; i < 10; i++) {
                var description = casper.fetchText(x('//*[@id="acDataId-local'+i+'"]/a')); //*[@id="acDataId-local0"]/a
                console.log(description);
                var target_date = casper.fetchText(x('//*[@id="dtDataId-local'+i+'"]/text()[1]')); 
                console.log(target_date);
                var target_location = casper.fetchText(x('//*[@id="veDataId-local'+i+'"]')); 
                console.log(target_location);

                console.log(i, description)

                casper.then(function () {

                    casper.open('http://localhost:1337/events', {
                        method: 'post',
                            data:   {
                            'description': description,
                            'target_date':  target_date,
                            'target_location':  target_location,
                        },
                        headers: {
                           "stuff":"stuff"
                        }
                    });
                });
            }
            this.echo('POST ' + i );
        });
    });
});


casper.run();

Console.log is outputting exactly when I want but it is only posting the last item. I tried to add casper.wait in a variety of places but it didn't seem to help!

回答1:

All then* and wait* functions in CasperJS are asynchronous step functions and JavaScript has function-level scope.

This means that the for-loop is executed immediately and several then() steps are scheduled to be executed after the for-loop is completely finished. At that point the function-level variables description, target_date, etc. will all have the value of the last i and i will be 10. Here is a general JavaScript example of that: JavaScript closure inside loops – simple practical example

You can either

change the two calls casper.then() and casper.open() to a single call casper.thenOpen() where the loop variables are passed to the function directly:

casper.thenOpen('http://localhost:1337/events', {
    method: 'post',
        data:   {
        'description': description,
        'target_date':  target_date,
        'target_location':  target_location,
    },
    headers: {
       "stuff":"stuff"
    }
});

or "close" the variables for each iteration by introducing an IIFE:

for  (var i = 0 ; i < 10; i++) {
    (function(){
        var description = casper.fetchText(x('//*[@id="acDataId-local'+i+'"]/a')); //*[@id="acDataId-local0"]/a
        console.log(description);
        var target_date = casper.fetchText(x('//*[@id="dtDataId-local'+i+'"]/text()[1]')); 
        console.log(target_date);
        var target_location = casper.fetchText(x('//*[@id="veDataId-local'+i+'"]')); 
        console.log(target_location);


        console.log(i, description)


        casper.then(function () {

            casper.open('http://localhost:1337/events', {
                method: 'post',
                    data:   {
                    'description': description,
                    'target_date':  target_date,
                    'target_location':  target_location,
                },
                headers: {
                   "stuff":"stuff"
                }
            });
        });
    })();
}

来源：https://stackoverflow.com/questions/35568147/casperjs-posting-only-the-last-item-multiple-times-from-my-for-loop

标签

javascript

loops

post

phantomjs

casperjs