好的,我正在Nodes的一个项目中工作,并且遇到了对象文字中的一个小问题,我有以下设置:
var required = {
directories : {
this.applicationPath : "Application " + this.application + " does not exists",
this.applicationPath + "/configs" : "Application config folder does not exists",
this.applicationPath + "/controllers" : "Application controllers folder does not exists",
this.applicationPath + "/public" : "Application public folder does not exists",
this.applicationPath + "/views" : "Application views folder does not exists"
},
files : {
this.applicationPath + "/init.js" : "Application init.js file does not exists",
this.applicationPath + "/controllers/index.js" : "Application index.js controller file does not exists",
this.applicationPath + "/configs/application.js": "Application configs/application.js file does not exists",
this.applicationPath + "/configs/server.js" : "Application configs/server.js file does not exists"
}
}
好吧你们中的很多人会看着这个,认为它看起来没问题,但是编译器一直告诉我我缺少一个:
(冒号),而不是,它看起来像是+
或者.
都影响编译器。
现在我相信(不确定),该对象文字是在编译时创建的,而不是运行时,这意味着动态变量(如this.applicationPath
连接和串联)将不可用:( :(
在不必重写大块代码的情况下,克服这种障碍的最佳方法是什么?
发布于 2018-03-19 17:42:31
在对象文本中(ECMA-262§11.1.5称它为“对象初始化程序”),键必须是以下之一:
所以你不能使用表达式作为初始化程序中的键。您可以使用带方括号表示法的表达式来访问属性。因此,要设置必须执行的表达式的属性:
var required = { directories : {}};
required.directories[this.applicationPath] = "Application " + this.application + " does not exists";
required.directories[this.applicationPath + "/configs"] = "Application config folder does not exists";
...
等等。由于this.applicationPath
被重用了很多,所以最好存储一个参考以帮助提高性能并减少代码量:
var a = this.applicationPath;
var required = { directories : {}};
var rd = required.directories;
rd[a] = "Application " + this.application + " does not exists";
rd[a + "/configs"] = "Application config folder does not exists";
...
[expression]: value
还有属性和方法名称的简写语法。
https://stackoverflow.com/questions/-100003641
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