javascript object variable key [duplicate]

Answer 1

Keep in mind you are defining an object there between the curly brackets. You can't use dots in property names. Assuming the displacement property is set somewhere else earlier, this will work for you:

$(selector).animate({settings: {direction: '+='+self.displacement+'px'}}, "slow" , function () {})

Answer 2

If the value is also a string you could use JSON.parse:

var a = 'key';
var b = 'value';
var test = JSON.parse('{"' + a + '":"' + b + '"}"');
//test = {key: 'value'}

Answer 3

AFAIK, you can't. Whatever is in front of the colon in the object literal notation will be automatically interpreted as a string. You will need to construct your object beforehand, and use the square bracket notation.

var options = {}
options[self.settings.direction] = '+=' + self.displacement + 'px';
$(selector).animate(options, "slow" , function () {});

Answer 4

You can access the string defined by a variable with toString(). so :

var obj = new Object;

obj.a = 0;
obj.b = 1;

var a = "b";

obj["a"]; // will output 0
obj[a.toString()] // will output 1