Javascript 使用字符串访问 JSON 或 JS 属性
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Access JSON or JS property using string
提问by jagdipa
I have a JSON array like this:
我有一个像这样的 JSON 数组：
_htaItems = [
{"ID":1,
"parentColumnSortID":"0",
"description":"Precondition",
"columnSortID":"1",
"itemType":0},
{"ID":2,
"parentColumnSortID":"0",
"description":"Precondition",
"columnSortID":"1",
"itemType":0}]
I want to update this by passing the ID, column name and new value to a function:
我想通过将 ID、列名和新值传递给函数来更新它：
function updateJSON(ID, columnName, newValue)
{
var i = 0;
for (i = 0; i < _htaItems.length; i++)
{
if (_htaItems[i].ID == ID)
{
?????
}
}
}
My question is, how do I update the value? I know I can do something like the following:
我的问题是，如何更新值？我知道我可以执行以下操作：
_htaItems[x].description = 'New Value'
But in my cause, the column name is being passed as a string.
但在我的原因中，列名作为字符串传递。
回答by T.J. Crowder
In JavaScript, you can access an object property either with literal notation:
在 JavaScript 中，您可以使用文字符号访问对象属性：
the.answer = 42;
Or with bracketed notation using a string for the property name:
或者使用带有属性名称的字符串的括号表示法：
the["answer"] = 42;
Those two statements do exactlythe same thing, but in the case of the second one, since what goes in the brackets is a string, it can be any expression that resolves to a string (or can be coerced to one). So all of these do the same thing:
这两个语句完全相同，但在第二个语句的情况下，由于括号中的内容是字符串，因此它可以是解析为字符串的任何表达式（或可以强制为字符串）。所以所有这些都做同样的事情：
x = "answer";
the[x] = 42;
x = "ans";
y = "wer";
the[x + y] = 42;
function foo() {
return "answer";
}
the[foo()] = 42;
...which is to set the answerproperty of the object theto 42.
...这是answer将对象的属性设置the为42.
So if descriptionin your example can't be a literal because it's being passed to you from somewhere else, you can use bracketed notation:
因此，如果description在您的示例中不能是文字，因为它是从其他地方传递给您的，您可以使用方括号表示法：
s = "description";
_htaItems[x][s] = 'New Value';
回答by sternr
_htaItems[x][columnName] = 'New Value'; Or did I misunderstand you?
_htaItems[x][columnName] = '新值'; 还是我误会了你？
回答by JAAulde
You need to use square bracket notation, just like you did for array index:
您需要使用方括号表示法，就像您对数组索引所做的一样：
_htaItems[i][columnName] = newValue;
回答by Digital Plane
Just do _htaItems[i][columnName] = newValue;. It will change the property specified in columnNameto newValue.
就做_htaItems[i][columnName] = newValue;。它将改变中指定的属性columnName来newValue。
