Warning: Added non-passive event listener to a scroll-blocking ‘touchstart’ event [duplicate]

Question

There is an update of the API of event listeners.

In short this:

document.addEventListener('touchstart', handler, true);

becomes this:

document.addEventListener('touchstart', handler, {capture: true});

Since in your case you attach event listener to touchstart it should be like that:

document.addEventListener('touchstart', handler, {passive: true});

This way you can setup in advance which exact event and if the passive interface is supported:

var passiveEvent = false;
try {
    var opts = Object.defineProperty({}, 'passive', {
        get: function () {
            passiveEvent = true;
        }
    });
    window.addEventListener("test", null, opts);
} catch (e) { }

// in my case I need both passive and capture set to true, change as you need it.
    passiveEvent = passiveEvent ? { capture: true, passive: true } : true;

//if you need to handle mouse wheel scroll
var supportedWheelEvent: string = "onwheel" in HTMLDivElement.prototype ? "wheel" :
    document.onmousewheel !== undefined ? "mousewheel" : "DOMMouseScroll";

And use like this:

elementRef.addEventListener("touchstart", handler, passiveEvent);

More details on passive event listeners here:
https://github.com/WICG/EventListenerOptions/blob/gh-pages/explainer.md

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