gremlins.md

   1 ---
   2 title: Gremlins.js
   3 category: JavaScript libraries
   4 layout: 2017/sheet
   5 updated: 2017-10-22
   6 weight: -1
   7 intro: |
   8   [Gremlins](https://github.com/marmelab/gremlins.js) is a JavaScript library to do "monkey-testing" by providing random user input (clicks, scrolls, and so on).
   9 ---
  10
  11 ## Example
  12
  13 ### Simple example
  14
  15 ```html
  16 <script src='https://cdn.jsdelivr.net/npm/gremlins/dist/gremlins.js'></script>
  17 <script>
  18 gremlins.createHorde().unleash()
  19 </script>
  20 ```
  21
  22 ![](https://camo.githubusercontent.com/130e101ee69d4d9b6f065df0a0404c861eb5ce18/687474703a2f2f7374617469632e6d61726d656c61622e636f6d2f746f646f2e676966?q=99)
  23
  24 ### Custom gremlins
  25
  26 ```js
  27 gremlins.createHorde()
  28   .allGremlins()
  29   .gremlin(function () {
  30     document.activeElement.blur()
  31   })
  32 ```
  33 {: data-line="3,4,5"}
  34
  35 Runs the given function at regular intervals.
  36
  37 ### Full example
  38
  39 ```js
  40 gremlins.createHorde()
  41   .gremlin(gremlins.species.formFiller())
  42   .gremlin(gremlins.species.clicker()
  43     .clickTypes(['click'])
  44     .canClick(element => { ··· })
  45     .showAction((x, y) => { ··· }))
  46   .gremlin(gremlins.species.scroller())
  47   .mogwai(gremlins.mogwais.alert())
  48   .mogwai(gremlins.mogwais.fps())
  49   .mogwai(gremlins.mogwais.gizmo().maxErrors(2))
  50   .unleash()
  51 ```
  52
  53 By default, all gremlins and mogwais species are added to the horde. Do it this way to customize gremlins.
  54
  55 See: [Specifying gremlins](https://github.com/marmelab/gremlins.js#setting-gremlins-and-mogwais-to-use-in-a-test)
  56
  57 ## Hooks
  58
  59 ### Before and after
  60
  61 ```js
  62 gremlins.createHorde()
  63   .before(function () {
  64     this.log('sync')
  65     console.profile('gremlins')
  66   })
  67   .after(function () {
  68     this.log('done')
  69     console.profileEnd()
  70   })
  71 ```
  72 {: data-line="2,6"}
  73
  74 ### Asynchronous
  75
  76 ```js
  77 gremlins.createHorde()
  78   .before(function (done) {
  79     setTimeout(() => {
  80       this.log('async')
  81       done()
  82     }, 500)
  83   })
  84 ```
  85 {: data-line="2"}
  86
  87 ## References
  88
  89 - [marmelab/gremlins.js](https://github.com/marmelab/gremlins.js)