div滑块超出边界（数组长度）

Question

my div slider ignores the borders that i've made, can't find the mistakes. PS right/left functions are called in tag attribute onclick:'slider.right()'. I'm just learning, I know that the elegance of the code is far from being ideal.

    let elArr = [];

let pusher = elArr.push(document.querySelectorAll('#scr>div'));
let elements = Array.from(elArr[0]);
let slider = {
  frame: 0,
  set: function(element){
    var container = document.getElementById('scr');
    container = element.style.visibility='visible';
  },

  init: function(){
    this.set(elements[this.frame]);
  },

  left: function(){
    elements[this.frame].style.visibility='hidden';
    this.frame--;
    if(this.frame<0)
    this.frame = elements.length - 1;
    this.set(elements[this.frame]);
  },

  right: function(){
    elements[this.frame].style.visibility='hidden';
    this.frame++;
    if(this.frame>elements.length)
    this.frame = 0;
    this.set(elements[this.frame]);
  }

};

window.onload = function(){
  slider.init();
}

Answer 1

One great guy just helped me, so there is an incorrect condition

if(this.frame>elements.length)

it drops 'frame' value, when current value is bigger then the number of elements in the array, but taking in consideration the fact, that indexation of the elements starts with 0, when frame is equal to elements.length - value becomes undefined, so frame value doesn't drop.

So, we need to change condition to a comparison == or to make it >=; thnx to user:186999 for the decision