函数仅实例化一个对象

函数仅实例化一个对象

本文介绍了Javascript:传递构造函数作为参数,函数仅实例化一个对象的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!

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

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

这篇关于Javascript:传递构造函数作为参数,函数仅实例化一个对象的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!

08-22 19:23