javascript - Leaking arguments

谁可以帮忙解释一哈 Leaking arguments 的概念

<script>

        Benchmark.prototype.setup = function() {

          
  function otherFunc(a, b) {
    return a + b;
  }
  
  function withArguments(x) {
    var a = arguments;
    return otherFunc.apply(x, Array.prototype.slice.call(a, 1));
  }
  
  function withCopy(x) {
    var a = [];
    var i, len = arguments.length;
    for (i = 1; i < len; i += 1) {
      a[i - 1] = arguments[i];
    }
    return otherFunc.apply(x, a);
  }