javascript - 如何在javascript中的数组内使用 "this"关键字？

Question

这里我有一个数组，其中包含 n 个与此类似的对象。

var views = [
  {
    id: "chart-0",
    datasource: "",
    type: "batch",
    context: "/analytics/device/stats/",
    schema: [
      {
        "metadata": {
          "names": [""],
          "types": [""]
        }
      }
    ],
    columns: [
      {
        "name": "month",
        "label": "month",
        "type": "linear",
      }, 
      {
        "name": "minValue",
        "label": "minValue",
        "type": "linear"
      }, 
      {
        "name": "maxValue",
        "label": "maxValue",
        "type": "linear",
        "axis": "y"
      }, 
      {
        "name": "time",
        "label": "time",
        "type": "time",
        "axis": "x"
      },
    ],
    callbacks: [
      {
        type: "click",
        callback: function() {}
      }
    ],
    data: function() {
      var COLUMNS = views[0].columns;
    }
  }
];

我想访问data函数中的一些字段。我可以简单地访问 id、数据源 this.id 或 this.datasource。如何使用 this 关键字而不是 views[0].columns 访问数据函数内的列

Answer 1

我知道您可以使用 this 关键字来分配 id、距离或任何其他属性的唯一方法是将数据传递到函数中。

// create a function and pass in a reference to the views array and specify the objects index you want to operate on.

function chanceProperty( views[0]) {
    var currentColumns = this.columns;  // gives you a reference to the objects columns array. "This" is a reference to the object that was passed in.

// you can then do your operations on the properties in that array either with a loop or by specifically targeting an object.

    currentColumns[1].name = "myNewMinValue";

// or

    currentColumns.forEach( function(val, idx) {
        currentColumns[idx].name = "allTheSame";
    });

}

更新

我想我明白你想做什么。您希望将一些 View 属性传递给数据函数。你不需要“这个”。您只需将所需的属性传递给数据函数即可。

data: function(id, dataSource, columns) {
    var COLUMNS = views[0].columns;
}