casper.js中的setInterval和this.wait

Question

I need to make a loop of 3 times and 2 seconds in between each iteration . I tried these 3 options:

Option 1

var casper = require('casper').create({
    verbose: false,
    logLevel: 'debug'
});

casper.start("http://google.com");

casper.on('remote.message', function(msg) {
    this.echo('remote message caught: ' + msg);
})

casper.thenEvaluate(function() {
    var x = 0;
    var intervalID = setInterval(function () {

       console.log("Using setInternal " + x);

       if (++x === 3) {
           window.clearInterval(intervalID);
       }
    }, 2000);

});

casper.run();

Observation : Nothing appeared because the script ended right away before the first setInterval being called.

Option 2

Replaced thenEvaluate() with then() below

for (i=0; i<3; i++) {
    this.wait(2000);
    this.echo('Using this.wait ' + i);
}

Observation : It outputs 3 times right away and then a long wait since this.wait() is async. This is not what I want because I want a delay in between.

Option 3 Replace the part in then() with this below. I was thinking about doing a recursive call to waitFunc() after each wait() being called.

var count = 0;
var waitFunc = function() {
    this.wait(2000, function() {
        if (count < 3) {
            casper.echo('Using this.wait ' + count);
            count++;
            waitFunc();
        }
    });

};

Observation : Nothing printed out on the screen.

So my question is: How to make this.wait or setInterval works in a loop of 3 times like this case?

Answer 1

Here's a sample implementation to solve your problem:

var casper = require('casper').create();
var last, list = [0, 1, 2, 3];

casper.start("http://google.fr/", function() {
    this.echo('google');
});

casper.on('remote.message', function(msg) {
    this.echo('remote message caught: ' + msg);
});

casper.thenEvaluate(function() {
    window.x = 0;
    var intervalID = setInterval(function() {
       console.log("Using setInternal " + window.x);
       if (++window.x === 3) {
           window.clearInterval(intervalID);
       }
    }, 500);
});

casper.each(list, function(self, i) {
    self.wait(500, function() {
        last = i;
        this.echo('Using this.wait ' + i);
    });
});

casper.waitFor(function() {
    return last === list[list.length - 1] && 3 === this.getGlobal('x');
}, function() {
    this.echo('All done.').exit();
});

casper.run(function() {});

Sample output:

$ casperjs test.js
google
remote message caught: Using setInternal 0
Using this.wait 0
remote message caught: Using setInternal 1
Using this.wait 1
remote message caught: Using setInternal 2
Using this.wait 2
Using this.wait 3
All done.
$