function x(a) vs function x(...a) the difference
function x(a) {console.log(a[0]); /*for a= ['b','c','d'] a[0] will be b*/ } function x(...a) { console.log(a[0]); /*for a= ['b','c','d'] a[0] will be ['b','c','d'] to get b you will need a[0][0]*/ /*in second case, the first array has only one term: the a array itself*/ }