Eventhandling

The following functions are supported: on,once,emit,removeListener,removeAllListeners. They behave exactly as described in the official NodeJS docs. There are some predefined events (error,init,end, command, log) which cover important WebdriverIO events.

Examples

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browser.on('error', function(e) {
    // will be executed everytime an error occurred
    // e.g. when element couldn't be found
    console.log(e.body.value.class);   // -> "org.openqa.selenium.NoSuchElementException"
    console.log(e.body.value.message); // -> "no such element ..."
})

Use the log() event to log arbitrary data, which can then be logged or displayed by a reporter:

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browser
    .init()
    .emit('log', 'Before my method')
    .click('h2.subheading a')
    .emit('log', 'After my method', {more: 'data'})
    .end();

All commands are chainable, so you can use them while chaining your commands

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var cnt;

browser
    .init()
    .once('countme', function(e) {
        console.log(e.elements.length, 'elements were found');
    })
    .elements('.myElem').then(function(res) {
        cnt = res.value;
    })
    .emit('countme', cnt)
    .end();

Note that you can’t execute any WebdriverIO commands or any other async operation within the listener function. Event handling comes handy when you want to log certain information but is not considered to be used to do action on certain events like taking a screenshot if an error happens. For use the onError hook in your wdio test runner configuration file.