在Javascript对象中打印所有属性

Question

我正在遵循代码学院的教程,我发现这很困难.

作业如下:

使用for-in循环打印出nyc的所有属性.

var nyc = {
    fullName: "New York City",
    mayor: "Michael Bloomberg",
    population: 8000000,
    boroughs: 5
};

// write your for-in loop here
for (var  in nyc){
    console.log(population);
}

Answer 1

你的语法不正确.循环中的var关键字for必须后跟变量名,在本例中为变量名propName

var propValue;
for(var propName in nyc) {
    propValue = nyc[propName]

    console.log(propName,propValue);
}

我建议你看一下基础知识:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...in

Answer 2

那这个呢:

var txt="";
var nyc = {
    fullName: "New York City",
    mayor: "Michael Bloomberg",
    population: 8000000,
    boroughs: 5
};

for (var x in nyc){
    txt += nyc[x];
}