什么是箭头函数 '() =>{}' 在 Javascript 中是什么意思?

我正在阅读 ScrollListView 的源代码和几个我看到使用 () => 的地方{}.

I was reading the source for ScrollListView and in several places I see the use of () => {}.

如第 25 行，

this.cellReorderThreshold = () => {
    var ratio = (this.CELLHEIGHT*this.cellsWithinViewportCount)/4;
    return ratio < this.CELLHEIGHT ? 0 : ratio;
};

第 31 行，

this.container.addEventListener('scroll', () => this.onScroll(), false);

第 88 行.

resizeTimer = setTimeout(() => {
    this.containerHeight = this.container.offsetHeight;
}, 250);

这是 function 的简写吗?如果有任何不同，那是什么?

Is this a shorthand for function and if it differs in any way, how so?