如何使用对象的括号表示法和属性名称的字符串向对象添加属性？

Question

I would like to use bracket notation for writing the object name so that I can reference it via a parameter. That's fine, but I run into trouble when I try to write the property name without passing it as a parameter. It's important that the property name is simply written out and not passed as a parameter. What is the correct syntax?

This example shows all of the syntax variations that I have tried:

 var foo = {}; bar('foo', 'cat'); function bar(object, prop) { // foo[prop] = 5; // = 5. This works, but this isn't the method I want to use. // [object]cat = 5; // = error // [object].cat = 5; // = undefined // [object]['cat'] = 5; // = undefined // [object][cat] = 5; // = error console.log('= ' + foo.cat); } 

Answer 1

As foo is declared as a global variable, the window object will contain that object internally.

So, you can do the following:

window[object]['cat'] = 5;

 var foo = {}; bar('foo'); console.log('= ' + foo.cat); function bar(object) { window[object]['cat'] = 5; } 

Answer 2

Just pass the actual object reference in:

 var foo ={} bar(foo, 'cat', 3); console.log('updated foo', foo); function bar(object, prop, val) { object[prop] = val; console.log('= ' + foo.cat); } 

Answer 3

function bar(object, prop) {
  this[object] = this[object] || {};
  this[object][prop] = 5;
  console.log(foo.cat)
}

hope this helps!