[英]Looking up nested properties in AJAX response, a case for try/catch?
So I'm writing a browser application that fetches data from many different public APIs (via JSONP) and uses that data to decorate my local records. 因此,我正在编写一个浏览器应用程序,该应用程序从许多不同的公共API(通过JSONP)中获取数据,并使用该数据来修饰我的本地记录。
Yeah, this could be done server-side beforehand but I'm not there yet. 是的,这可以事先在服务器端完成,但我还没有。
I've never used try/catch in JavaScript before. 我以前从未在JavaScript中使用过try / catch。 In trying to lookup response.foo.bar.baz
in a response that's liable to change, would this be a good time to use it? 尝试在易于更改的response.foo.bar.baz
中查找response.foo.bar.baz
时,是使用它的好时机吗?
Alternatively, is there a more elegant way to lookup deeply nested properties and not throw an error if it can't be found? 或者,是否有更优雅的方法来查找深层嵌套的属性,如果找不到错误,则不抛出错误?
You could do something like this: 您可以执行以下操作:
response && response.foo && response.foo.bar && response.foo.bar.baz
If one of the nested properties doesn't exist it will return undefined
else it will return the contents of response.foo.bar.baz
. 如果其中一个嵌套属性不存在,它将返回undefined
否则它将返回response.foo.bar.baz
的内容。
Alternative you could use this function: 或者,您可以使用以下功能:
function getNestedProperty(firstObject, propertiesArray)
{
if(firstObject instanceof Object)
{
var currentObject = firstObject;
for(var i = 0; i < propertiesArray.length; i++)
{
if(currentObject.hasOwnProperty(propertiesArray[i]))
{
currentObject = currentObject[propertiesArray[i]];
}
else
{
return false;
}
}
return currentObject;
}
else
{
return false;
}
}
Usage: 用法:
getNestedProperty(response, ['foo', 'bar', 'baz']);
It's probably easier to write: 编写起来可能更容易:
try {
response.foo.bar.baz;
}
catch (e) {
//oops
}
Than: 比:
if( response && response.foo && response.foo.bar && "baz" in response.foo.bar ) {
}
else {
//oops
}
Given that the alternative is something like: 鉴于替代方案是这样的:
if ('foo' in response &&
'bar' in response.foo &&
'baz' in response.foo.baz)
{
...
}
it sounds like a try / catch
block might be a good option in this case! 听起来在这种情况下, try / catch
块可能是一个不错的选择!
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