[英]for…of iteration and destructuring with an object inside an array
根据Mozilla文档 ,这里是如何在for of
循环中使用解构:
var people = [
{
name: 'Mike Smith',
family: {
mother: 'Jane Smith',
father: 'Harry Smith',
sister: 'Samantha Smith'
},
age: 35
},
{
name: 'Tom Jones',
family: {
mother: 'Norah Jones',
father: 'Richard Jones',
brother: 'Howard Jones'
},
age: 25
}
];
for (var {name: n, family: {father: f}} of people) {
console.log('Name: ' + n + ', Father: ' + f);
}
// "Name: Mike Smith, Father: Harry Smith"
// "Name: Tom Jones, Father: Richard Jones"
我的问题是,如果family
对象位于数组中,正确的解构语法是什么,如下所示:
var people = [
{
name: 'Tom Jones',
family: [
{
mother: 'Norah Jones',
father: 'Richard Jones',
brother: 'Howard Jones'
}
],
age: 25
}
];
(注意额外的[方括号])
尝试使用以下方法进行结构化:
for (var {name: n, family[0]: {father: f}} of people) {
console.log('Name: ' + n + ', Father: ' + f);
}
在方括号处出现Unexpected token
错误。
所以在这个例子中,我如何使用解构来为f
赋值?
您希望表示数组结构,而不是数组索引访问。
var people = [{ name: 'Tom Jones', family: [{ mother: 'Norah Jones', father: 'Richard Jones', brother: 'Howard Jones' }], age: 25 }]; // Describe the structure -v-----------v for (var {name: n, family: [{father: f}]} of people) { console.log('Name: ' + n + ', Father: ' + f); }
当然,这假设您只想要第一个成员。 如果您需要更多,可以使用其余语法。
var people = [{ name: 'Tom Jones', family: [{ mother: 'Norah Jones', father: 'Richard Jones', brother: 'Howard Jones' }], age: 25 }]; for (var {name: n, family: [{father: f}, ...rem]} of people) { console.log('Name: ' + n + ', Father: ' + f); console.log("Remaining values: %s", rem.length); }
您可以使用数组解构(简单地忽略任何剩余的数组元素):
// vv vv
for (var {name: n, family: [ {father: f} ] } of people)
// ...
或者,由于数组只是对象,因此您可以使用索引作为键的对象解构:
// vvvvv vv
for (var {name: n, family: { 0: {father: f} } } of people)
// ...
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