javascript - How to add dynamic properties to an object

Question

var options = {pageName: 'index', position: 1800}
var obj = {}
现在要把这个属性添加到obj中变成
obj = {
  index:{position: options.position}
}
前面的index根据上面的pageName动态变化如何处理？

Answer 1

var options = {pageName: 'index', position: 1800}
var obj = {} 
obj = {
  [options.pageName]:{position: options.position}
}

Answer 2

var result = {};
function objSet(keyName,targetName){
    var obj = {};
    for(var key in options){
        if( key == keyName){
            var temp = {};
            temp[targetName] = options[targetName];
            obj[keyName] = temp;
            break;
        }
    }
    return obj;
}
result = objSet("pageName","position");
//这样？