javascript - array.push() 不起作用，即使数组对象已明确定义并在范围内

Question

我有以下简单的 JavaScript 代码(合并排序)，由于某种原因，将值推送到数组在 merge() 函数中不起作用(jsfiddle 中的第 26 和 31 行)。它与数组的范围有关吗？但是它在合并函数中有明确的定义。我在这里遗漏了一些非常概念性的东西。任何帮助将不胜感激。

https://jsfiddle.net/kalyanc/pu8988qc/

var A = [5,2,4,7,1,3,2,6];      

mergeSort(A);

function mergeSort(array) {
  if (array.length < 2) {
    return array;
  }
  var midpoint = parseInt(array.length/2);
  var left = array.slice(0, midpoint);
  var right = array.slice(midpoint, array.length);
  alert("Calling merge with arrays, " + left + " and " + right);
  return merge(mergeSort(left), mergeSort(right));
}

function merge(L, R) {
  var Output = []; // Output array is clearly defined here.

  var m = 0;
  var n = 0;

  while(m < L.length && n < R.length)
  {
    for (var x = 0; x < Math.min(L.length, R.length); x++) {
      if (L[m] <= R[n]) {
        Output.push(L[m]); // Does not work! 
        m++;        
        alert("Output from merge is array " + toString(Output)); 
        // Alerts: Output from merge is array [object Undefined]
      } else {
        Output.push(R[n]); // Does not work!
        n++;
        alert("Output from merge is array " + toString(Output));
        // Alerts: Output from merge is array [object Undefined]
      }             
    }
  }         

  // Check if either L or R have an element left
  if (m < L.length) {
    for (var o = m; o < L.length; o++) {                    
      Output.push(L[o]);
    }               
  }
  if (n < R.length) {
    for (var o = n; o < R.length; o++) {
      Output.push(R[o]);
    }               
  }
  return Output;                    
}

Answer 1

toString是对象原型(prototype)函数，应该在对象上调用。

在您的特定实例中，不要调用 toString(Output)，而是尝试使用 Output.toString()。

jsfiddle