Wait for some time in PhantomJS between console logs in the page context

Question

I need to wait some time in PhantomJS. I searched a lot but didn't find an answer. I try this code inside page.open but it doesn't work.

var interval = window.setInterval(function(){ 
    console.log("works");
    clearInterval(interval); 
}, 3000);

I also tried setTimeout but it also didn't help

window.setTimeout(function(){ 
    console.log("works");
}, 3000);

What is a solution for waiting some seconds?

I need to wait 3 seconds between logs: jquery included and works. But these logs appear in console simultaneously.

var page = require("webpage").create();
var url = "https://www.youtube.com";

page.open(url, function(status) {
    if (status == "success"){
        console.log(status);
        if (page.injectJs("jquery.min.js")){
            console.log("jquery included");
            page.evaluate(function(){
                setTimeout(function(){       
                }, 3000);
            });
            console.log("works");
            phantom.exit();
        }       
    }
    else{
        console.log(status);
        phantom.exit();
    }
});

It can be duplicate, but I can't understand yet what should I do with `page.evaluate`. — levshkatov, Mar 20 '16 at 16:47
What do you expect to happen? Are you trying to wait inside of the page context (inside `page.evaluate`) and wondering why nothing is printed to the console? — Artjom B., Mar 20 '16 at 16:58
@ArtjomB. I have a cycle. In it I click on a button and need to wait some time and then I reload page. In other words, I have two `console.log` and need to `setTimeout` between them — levshkatov, Mar 20 '16 at 17:01
As for every question which seeks debugging help, what's your definition of *"it doesn't work"*? What do you see and what do you expect to see? Please be more specific. It also wouldn't hurt to show a bigger part of your script to rule out simple mistakes. — Artjom B., Mar 20 '16 at 17:15
@levshkatov you cannot `setTimeout` *between* them, but you can run your second `console.log` in the callback of the `setTimeout` which is effectively the same thing. If this is what youre truly wanting to do: `setTimeout(function() { console.log('works') }, 3000)` is what you want inside the `page.evaluate` — ginman, Mar 20 '16 at 17:22
You exit phantom before the timeout callback ever executes. I think that's your problem. Move phantom.exit() to inside the setTimeout callback if you want to wait for a few seconds. setTimeout doesn't halt execution of the rest of the script. — dannyjolie, Mar 20 '16 at 17:24
@dannyjolie Also is for `phantom.exit()`. I can't run it inside `evaluate`. — levshkatov, Mar 20 '16 at 17:29
@levshkatov I see that in the docs that console wont show, and you have no access to the `phantom` object. You can however run pretty much any other code inside of it. At this point, we would need to know what code you are really trying to run, as `setTimeout` is most likely the solution. You can also add a listener to pipe the `console.log` messaging - see the last section in http://phantomjs.org/api/webpage/method/evaluate.html — ginman, Mar 20 '16 at 17:34
Ah, that's true. It's been a while since I used PhantomJS :) Anyway, this should be what you're looking for, see answer 2 http://stackoverflow.com/questions/11340038/phantomjs-not-waiting-for-full-page-load — dannyjolie, Mar 20 '16 at 17:36
@ginman It also didn't help if I put `console.log` inside `setTimeout` — levshkatov, Mar 20 '16 at 17:43

score 6 · Accepted Answer · answered Mar 20 '16 at 17:43

This is a collection of what is wrong:

JavaScript has no sleep function like other languages, because it is single-threaded. This means that a sleep would effectively stop all other processing. So, you cannot use
```
console.log("1");
setTimeout(function(){}, 5000);
console.log("2");
```
and expect 2 to be printed 5 seconds after 1. 2 will be printed immediately after 1. You need to use the asynchronous nature of JavaScript:
```
console.log("1");
setTimeout(function(){
    console.log("2");
}, 5000);
```
phantom.exit() must be called when you're done with the script. This means that you need to call it from the setTimeout callback.
page.evaluate is the sandboxed page context. You cannot use variables defined outside. As such, you cannot use phantom.exit() inside of page.evaluate(), but you can use the window.callPhantom/page.onCallback pair to get a message from the page context.
If you want to receive console messages from the page context, you need to provide a onConsoleMessage event handler.

Full script:

var page = require("webpage").create();
var url = "https://www.youtube.com";

page.onCallback = function(data){
    if (data.type === "exit") {
        phantom.exit();
    }
};
page.onConsoleMessage = function(msg){
    console.log("remote: " + msg);
};
page.open(url, function(status) {
    if (status == "success"){
        console.log(status);
        if (page.injectJs("jquery.min.js")){
            console.log("jquery included");
            page.evaluate(function(){
                setTimeout(function(){
                    console.log("works");
                    window.callPhantom({type: "exit"});
                }, 3000);
            });
        }       
    }
    else{
        console.log(status);
        phantom.exit();
    }
});

Wait for some time in PhantomJS between console logs in the page context

1 Answers1

Full script: