README.md needs an example gif of how effective every 30 seconds is

Hi, great idea, I would love to use it, but:

/app # tlapse -- localhost:3000

results in:

Screenshots directory: ./tlapse
Interval: 1m
01:21:14
01:22:15

but the content of the directory stays empty.

I run wget localhost:3000 and it returns an index.html that I also see in the browser.

Changing the directory, resolution, interval didn't change anything.

I'm using it inside a Docker container FROM mhart/alpine-node:7.4.

I am running it as root, and did the npm install -g tlapse as root.

Running tlapse --every 45s --directory ./screens -- https://localhost:8080 gives:

Screenshots directory: ./screens
Interval: 45s
10:42:32 ✔ Generated 1 screenshot from 1 url and 1 size

And a 6kb blank image:

The default tlapse file format of 'hh:MM:ss` makes invalid filenames on windows, so no screenshots are ever written.

Something like hh-MM-ss might be more cross-platform friendly.

Seems a bit strange that the day isn't part of the filename as well, since development may often stretch out over multiple days.

Trying to run tlapse for the first time and I'm getting an error.

$ tlapse -- localhost:3000

Screenshots directory: ./tlapse
Interval: 1m
C:\Users\Patrick\Documents\Code\gw2api-explorer\node_modules\tlapse\index.js:67
    if (latestFile.indexOf('.png.') !== -1) {
                  ^

TypeError: Cannot read property 'indexOf' of undefined
    at run (C:\Users\Patrick\Documents\Code\gw2api-explorer\node_modules\tlapse\index.js:67:19)
    at Object.<anonymous> (C:\Users\Patrick\Documents\Code\gw2api-explorer\node_modules\tlapse\index.js:85:1)
    at Module._compile (module.js:571:32)
    at Object.Module._extensions..js (module.js:580:10)
    at Module.load (module.js:488:32)
    at tryModuleLoad (module.js:447:12)
    at Function.Module._load (module.js:439:3)
    at Module.runMain (module.js:605:10)
    at run (bootstrap_node.js:420:7)
    at startup (bootstrap_node.js:139:9)

The tlapse directory is created successfully, but it seems like it's barfing when trying to find a previous screenshot when one doesn't exist. I guess I'll try and make one manually?

I know that you can set the width and height by specifying them as options, but if you don't already know the height of the page, it would be nice to add an option to have that calculated for you.

Something like tlapse localhost:3000 -v 1300 x auto or similar.

I get different results in browser and on screenshot.

Hi there,

I can't start tlapse, here is console output:

tlapse --every 30s -- localhost:8080

/usr/local/lib/node_modules/tlapse/node_modules/execa/index.js:2
const childProcess = require('child_process');
^^^^^
SyntaxError: Use of const in strict mode.
    at Module._compile (module.js:439:25)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Module.require (module.js:364:17)
    at require (module.js:380:17)
    at Object.<anonymous> (/usr/local/lib/node_modules/tlapse/index.js:5:13)
    at Module._compile (module.js:456:26)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)

Ubuntu 14.04.5 LTS

nodejs --version
v0.10.25

npm --version
1.3.10