new URLSearchParams(iterable)

• iterable <Iterable> 一个其元素为键值对的可迭代对象

使用可迭代的映射实例化一个新的 URLSearchParams 对象，其方式类似于 Map 的构造函数。iterable 可以是一个 Array 或任何可迭代对象。这意味着 iterable 可以是另一个 URLSearchParams，在这种情况下，构造函数将简单地创建所提供 URLSearchParams 的克隆。iterable 的元素是键值对，并且它们本身可以是任何可迭代对象。

【Instantiate a new URLSearchParams object with an iterable map in a way that is similar to Map's constructor. iterable can be an Array or any iterable object. That means iterable can be another URLSearchParams, in which case the constructor will simply create a clone of the provided URLSearchParams. Elements of iterable are key-value pairs, and can themselves be any iterable object.】

允许重复的键。

【Duplicate keys are allowed.】

let params;

// Using an array
params = new URLSearchParams([
  ['user', 'abc'],
  ['query', 'first'],
  ['query', 'second'],
]);
console.log(params.toString());
// Prints 'user=abc&query=first&query=second'

// Using a Map object
const map = new Map();
map.set('user', 'abc');
map.set('query', 'xyz');
params = new URLSearchParams(map);
console.log(params.toString());
// Prints 'user=abc&query=xyz'

// Using a generator function
function* getQueryPairs() {
  yield ['user', 'abc'];
  yield ['query', 'first'];
  yield ['query', 'second'];
}
params = new URLSearchParams(getQueryPairs());
console.log(params.toString());
// Prints 'user=abc&query=first&query=second'

// Each key-value pair must have exactly two elements
new URLSearchParams([
  ['user', 'abc', 'error'],
]);
// Throws TypeError [ERR_INVALID_TUPLE]:
//        Each query pair must be an iterable [name, value] tuple 拷贝