Question

我正在尝试使用外部select文件中的数据填充json元素。

var dropDown = document.getElementById('dropdown');

request.onload = function() {
  if (request.status >= 200 && request.status < 400) {
    // success
    data = JSON.parse(request.responseText);
    console.log(data);

    for (var i = 0, len = data.length; i < len; i++) {
        alert('FOO');
        var data = data[i];
        dropDown.innerHTML(option.name);
    }
};

JSON

{
    "TopLevel": {
        "Second": [
            "data",
            "data",
            "data",
            "data"
        ],
        "Second": [
            {
                "ThirdLabel": "data",
                "ThirdID": "data"
            },
            {
                "ThirdLabel": "data",
                "ThirdID": "data"
            },
            {
                "ThirdLabel": "data",
                "ThirdID": "data"
            }
        ]
    },
    "TopLevel": {
        "Second": [
            "data",
            "data",
            "data",
            "data"
        ],
        "Second": [
            {
                "ThirdLabel": "data",
                "ThirdID": "data"
            },
            {
                "ThirdLabel": "data",
                "ThirdID": "data"
            },
            {
                "ThirdLabel": "data",
                "ThirdID": "data"
            }
        ]
    }
}

我已经可以使用上述方法成功返回数据，但是由于某些原因，我无法运行循环，并且不确定自己在做什么错。

没有控制台错误，我的警报也不会触发...

Answer 1

向选项中添加选项的最佳方法是根据W3schools Select add() Method使用document.createElement("option")。

var json = { "data": ["orange", "banana", "apple", "pear"] };

var dropdown = document.getElementById("dropdown");

for (var i = 0; i < json.data.length; i++) {
  var option = document.createElement("option");
  option.text = json.data[i];
  option.value = json.data[i];
  dropdown.add(option);
}

<select id="dropdown"></select>

Answer 2

您需要以这种方式编写代码。

数据正在返回#include <string.h> void mat_insert(const struct matrix *s, struct matrix *d, int r, int c) { // copy source matrix s to destination matrix d at row r, column c for (int i = 0; i < s->M; i++) // for each row memcpy(d->data+(r+i)*d->N+c, s->data+i*s->N, s->N*sizeof*s->data); } struct matrix *mat_directsum(const struct matrix *a, const struct matrix *b) { struct matrix *c = malloc(sizeof *c); if (!c) return NULL; c->M = a->M + b->M; c->N = a->N + b->N; int n = c->M * c->N; c->data = calloc(n, sizeof *c->data); if (!c->data) return free(c), NULL; mat_insert(a, c, 0, 0); // copy a to c at row 0, column 0 mat_insert(b, c, a->M, a->N); // copy b to c at row a->M, column a->N return c; }，因此数据长度为object {}，并且循环未运行。

您需要选择要返回数组的特定数据。

例如：undefined

data.TopLevel.Second

var data = {
  "TopLevel": {
    "Second": [
      "data",
      "data",
      "data",
      "data"
    ],
    "Second": [{
        "ThirdLabel": "data",
        "ThirdID": "data"
      },
      {
        "ThirdLabel": "data",
        "ThirdID": "data"
      },
      {
        "ThirdLabel": "data",
        "ThirdID": "data"
      }
    ]
  },
  "TopLevel": {
    "Second": [
      "data",
      "data",
      "data",
      "data"
    ],
    "Second": [{
        "ThirdLabel": "data",
        "ThirdID": "data"
      },
      {
        "ThirdLabel": "data",
        "ThirdID": "data"
      },
      {
        "ThirdLabel": "data",
        "ThirdID": "data"
      }
    ]
  }
}

var dropDown = document.getElementById('dropdown');
debugger;
var options = "";
for (var i = 0, len = data.TopLevel.Second.length; i < len; i++) {
  var item = data.TopLevel.Second[i];
  options += "<option> " + item.ThirdID + "</option>"
}
document.getElementById("dropdown").innerHTML = options;

使用Vanilla JS和JSON文件填充选择元素

2 个答案: