更新时间:2023-01-16 23:09:01
首先,因为你是JSON的新手,有些术语修正可以帮助你:JSON是一个字符串,对象因此是 J ava S 脚本 O 对象 N 标签的缩写。您所拥有的内容通常称为POJO或 P 提供 O ld J avascript O 对象。他们是不同的。
First, since you are new to JSON, a little terminology correction to help you out: JSON is a string and not an object hence it's abbreviation of JavaScript Object Notation. What you have is colloquially referred to as a POJO or Plain Old Javascript Object. They are different.
现在提出你的问题。您有两种方法:
Now for your question. You have two approaches:
第一个解决方案是使用poly -fill在 find :
The first solution would be to use the poly-fill provided in the documentation for find
:
var countryData = data.find(function(element, index, array) {
return element.Id === 'SWE';
});
countryData.Population // 9592552
第二种方法基本上是重新创建如果你选择这个选项,我将把它留给你作为一个练习来学习。
The second method is basically recreating the poly-fill in a whatever manner you choose and if you choose that option I'll leave that up to you as an exercise to learn from.
if (!Array.prototype.find) {
Array.prototype.find = function(predicate) {
if (this == null) {
throw new TypeError('Array.prototype.find called on null or undefined');
}
if (typeof predicate !== 'function') {
throw new TypeError('predicate must be a function');
}
var list = Object(this);
var length = list.length >>> 0;
var thisArg = arguments[1];
var value;
for (var i = 0; i < length; i++) {
value = list[i];
if (predicate.call(thisArg, value, i, list)) {
return value;
}
}
return undefined;
};
}
var data = [{
"Id": "SWE",
"Country": "Sweden",
"Population": 9592552
}, {
"Id": "NOR",
"Country": "Norway",
"Population": 5084190
}];
function display(e) {
console.log("E", e);
var countryData = data.find(function(element, index, array) {
return element.Id === e;
});
console.log(countryData.Population);
}
display('SWE');