Javascript：传递构造函数作为参数，函数仅实例化一个对象 [英] Javascript: Passing constructor as parameter, function instantiates only a single object

问题描述

我想要一个函数来创建一个网格，并在每个插槽中插入一个唯一的对象。这里的关键是，函数应该接受构造函数作为参数（因为可能有多个构造函数可能需要通过此函数调用），但实例化多个对象。

I'd like a certain function to create a grid and insert a unique object in each slot. The key here is, the function should accept the constructor as a parameter (as there can be multiple constructors that may need to be called via this function), but instantiate multiple objects.

现在，我有：

//constructor
function NewObj(){
...some stuff
}

//function to construct. Needed since grid function accepts non-constructors as well
function buildNewObj(){ return new NewObj();}

//here is the grid function that takes size and which data to pre-insert as parameters
function newGrid(rows,cols,dataFunction){

var customGrid = [];

for(row=0;row<rows;row++){
       var customRow = [];
       for(col=0;col<cols;col++){
             var data = dataFunction;
             customRow.push(data);
       }
       customGrid.push(customRow);
}

return customGrid;
}

调用方式：

var myGrid = newGrid(3,3,buildNewObj());

myGrid的结果是一个3x3网格，它们都链接到同一个对象。如果我在buildNewObj（）函数中放置一个Alert（）并运行它，则警报只显示一次。

The results of myGrid are a 3x3 grid that all link to the same object. If I place an Alert() within the buildNewObj() function and run this, the alert displays only once.

如果我们更改newGrid中的代码，作为参数，而是直接引用它，像这样：

If we change the code within newGrid to not take the constructor as a parameter, but rather directly reference it like so:

var data = buildNewObj();

而不是

var data = dataFunction;

然后网格中的每个插槽都有自己唯一的对象。

Then every slot within the grid gets its own unique object.

如何在网格的每个槽中获取一个唯一的对象，同时仍通过参数传递构造函数？

How can I get a unique object in each slot of the grid while still passing the constructor function via parameter?

谢谢！

推荐答案

将 buildNewObject 作为函数传递，而不是调用它并传递结果。

Pass the buildNewObject as a function, instead of calling it and passing its result.

function newGrid(rows,cols,dataFunction) {
    var customGrid = [];
    for (var row=0;row<rows;row++){
        var customRow = [];
        for (var col=0;col<cols;col++){
            var data = dataFunction(); // yes, it's a function
                                       // we need (want) to call it
            customRow.push(data);
        }
        customGrid.push(customRow);
    }
    return customGrid;
}

var myGrid = newGrid(3,3,buildNewObj); // no parenthesis, no invocation

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