getCurrentTabId = function getCurrentTabId() {
    return this.unify(this.windowHandle(), {
        extractValue: true
    });
}
Retrieve the current window handle.

<example>
    :getCurrentTabId.js
    it('should return the current tab id', function () {
        browser.url('http://webdriver.io')

        var tabId = browser.getCurrentTabId()
        console.log(tabId)
        // outputs something like the following:
        // "CDwindow-C43FB686-949D-4232-828B-583398FBD0C0"
    })
</example>

@alias browser.getCurrentTabId
@return {String} the window handle URL of the current focused window
@uses protocol/windowHandle
@type window