I currently have a Javascript function that uses a string to reference an object name and acces its properties. I'm currently using eval() to get the the desired effect which I know is very, very wrong. Here is an example of how I'm currently achieving what I want:
var stringToObjectRef = function() {
var myTestVar = "myTestObject";
var myTestObject = { 'item1' : 100, 'item2' : 12, 'item4' : 18 };
var myValue = eval(myTestVar + '.item1');
alert(myValue);
}();
I've tried using something like [myTestVar].item1, but this returns undefined. What is the correct syntax to achieve this?
Thanks in advance.
If you're talking about the item1
part, you're looking for:
myValue = myTestObject["item1"];
No need for eval
. (There almost never is.)
If you're talking about getting at the myTestObject
variable using a "myTestObject" string, you want to refactor the code so you're not doing that, rather than using eval
. Unfortunately the variable object used for symbol resolution within the function is not accessible directly. The refactor could just use an object explicitly:
var stringToObjectRef = function() {
var objects = {};
var myTestVar = "myTestObject";
objects.myTestObject = { 'item1' : 100, 'item2' : 12, 'item4' : 18 };
var myValue = objects[myTestVar].item1;
alert(myValue);
}();
Off-topic, I don't recall precisely why, but if you're going to execute that anonymous function immediately like that, you need to put the function expression in parentheses:
var x = (function() { return 5; })();
rather than
var x = function() { return 5; }();
Again, I don't recall why, and whether it was because of an implementation bug in a popular interpreter or an actual requirement of the syntax.
Try this instead:
var stringToObjectRef = function() {
var myTestObject = { 'item1' : 100, 'item2' : 12, 'item4' : 18 };
var myValue = myTestObject['item1'];
alert(myValue);
}();
eval("myTestObject[\\"item1\\"") should do the trick, as myTestObject.item1 is shorthand for myTestObject["item1"]
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.