Is there a way to use TypeScript to prevent accidental global access?

I just spent 2 hours tracking down this issue:

• We have a class with a prototype method called focus()
• Our code was calling focus(), but it should have been calling this.focus()
• The code compiled fine, because window.focus() shares the same signature as our focus() method

Is there a way to throw a compile time error when implicitly accessing global methods (on window, global, etc.)?

If not, a compiler flag would be extremely helpful. I would happily be more explicit about commonly used globals (window.setTimeout, window.document, …) if it meant I could more easily catch insidious bugs like this one.

Full commit here: https://github.com/coatue/SlickGrid/commit/0f8bab3fa9968173d749ccdf535c88f3a526ca8b.

[niieani]

How about adding a tsconfig.json option such as:

explicitGlobals: true

With it on, if you’d write name, location or focus() without being explicit, i.e. window.name, while at the same time, if those names aren’t declared in the local scope, it would mark those references as errors. At the same time there could be a quick fix to either reference the local scope, in case of a similar problem to @bcherny (missing this) or to reference the global scope explicitly, (i.e. name => window.name).

This would require being able to mark variables such as window, self and global as globals, instead of redefining each of their properties globally (as is currently done).

This would also mean that given the option is true, and one declared a $ global which is typeof jQuery, any usage would trigger the above error, unless you’d use it as window.$ or using import * as $ from 'jQuery'.

[jahooma]

Ok, while typescript is working on this, here’s a solution.

If you use eslint, you can just copy the below rule into your .eslintrc.

I left out some of the more commonly used variables like document, setTimeout, and addEventListener, but otherwise it is most of them.

“no-restricted-globals”: [“error”,“postMessage”,“blur”,“focus”,“close”,“frames”,“self”,“parent”,“opener”,“top”,“length”,“closed”,“location”,“origin”,“name”,“locationbar”,“menubar”,“personalbar”,“scrollbars”,“statusbar”,“toolbar”,“status”,“frameElement”,“navigator”,“customElements”,“external”,“screen”,“innerWidth”,“innerHeight”,“scrollX”,“pageXOffset”,“scrollY”,“pageYOffset”,“screenX”,“screenY”,“outerWidth”,“outerHeight”,“devicePixelRatio”,“clientInformation”,“screenLeft”,“screenTop”,“defaultStatus”,“defaultstatus”,“styleMedia”,“onanimationend”,“onanimationiteration”,“onanimationstart”,“onsearch”,“ontransitionend”,“onwebkitanimationend”,“onwebkitanimationiteration”,“onwebkitanimationstart”,“onwebkittransitionend”,“isSecureContext”,“onabort”,“onblur”,“oncancel”,“oncanplay”,“oncanplaythrough”,“onchange”,“onclick”,“onclose”,“oncontextmenu”,“oncuechange”,“ondblclick”,“ondrag”,“ondragend”,“ondragenter”,“ondragleave”,“ondragover”,“ondragstart”,“ondrop”,“ondurationchange”,“onemptied”,“onended”,“onerror”,“onfocus”,“oninput”,“oninvalid”,“onkeydown”,“onkeypress”,“onkeyup”,“onload”,“onloadeddata”,“onloadedmetadata”,“onloadstart”,“onmousedown”,“onmouseenter”,“onmouseleave”,“onmousemove”,“onmouseout”,“onmouseover”,“onmouseup”,“onmousewheel”,“onpause”,“onplay”,“onplaying”,“onprogress”,“onratechange”,“onreset”,“onresize”,“onscroll”,“onseeked”,“onseeking”,“onselect”,“onstalled”,“onsubmit”,“onsuspend”,“ontimeupdate”,“ontoggle”,“onvolumechange”,“onwaiting”,“onwheel”,“onauxclick”,“ongotpointercapture”,“onlostpointercapture”,“onpointerdown”,“onpointermove”,“onpointerup”,“onpointercancel”,“onpointerover”,“onpointerout”,“onpointerenter”,“onpointerleave”,“onafterprint”,“onbeforeprint”,“onbeforeunload”,“onhashchange”,“onlanguagechange”,“onmessage”,“onmessageerror”,“onoffline”,“ononline”,“onpagehide”,“onpageshow”,“onpopstate”,“onrejectionhandled”,“onstorage”,“onunhandledrejection”,“onunload”,“performance”,“stop”,“open”,“print”,“captureEvents”,“releaseEvents”,“getComputedStyle”,“matchMedia”,“moveTo”,“moveBy”,“resizeTo”,“resizeBy”,“getSelection”,“find”,“createImageBitmap”,“scroll”,“scrollTo”,“scrollBy”,“onappinstalled”,“onbeforeinstallprompt”,“crypto”,“ondevicemotion”,“ondeviceorientation”,“ondeviceorientationabsolute”,“indexedDB”,“webkitStorageInfo”,“chrome”,“visualViewport”,“speechSynthesis”,“webkitRequestFileSystem”,“webkitResolveLocalFileSystemURL”, “openDatabase”],