函数嵌套函数（根据对象属性对数组进行排序）

例：根据对象属性对数组进行排序

function createComparisonFunction(propertyName){
    return function(obj1,obj2){
        var val1 = obj1[propertyName];
        var val2 = obj2[propertyName];
        if(val2<val2){
            return -1;
        }else if(val1>val2){
            return 1;
        }else{
            return 0;
        }
    }
}  
var data = [{name:"bill",age:10},{name:"lily",age:2}];
data.sort(createComparisonFunction("age"))；