如果我有以下对象数组:
[ { id: 1, username: 'fred' }, { id: 2, username: 'bill' }, { id: 2, username: 'ted' } ]
是否有一种方法通过数组循环检查特定的用户名值是否已经存在，如果它不做任何事情，但如果它没有添加一个新对象到数组的用户名(和新ID)?
谢谢!
当前回答
你也可以试试这个
const addUser = (name) => {
if (arr.filter(a => a.name == name).length <= 0)
arr.push({
id: arr.length + 1,
name: name
})
}
addUser('Fred')
其他回答
function number_present_or_not() {
var arr = [2, 5, 9, 67, 78, 8, 454, 4, 6, 79, 64, 688];
var found = 6;
var found_two;
for (i = 0; i < arr.length; i++) {
if (found == arr[i]) {
found_two = arr[i];
break;
}
}
if (found_two == found) {
console.log('number present in the array');
} else {
console.log('number not present in the array');
}
}
点击这里查看:
https://stackoverflow.com/a/53644664/1084987
你可以在后面创建if条件，比如
if(!contains(array, obj)) add();
Lodash中的xorWith可以用来实现这一点
let objects = [ { id: 1, username: 'fred' }, { id: 2, username: 'bill' }, { id: 2, username: 'ted' } ]
let existingObject = { id: 1, username: 'fred' };
let newObject = { id: 1729, username: 'Ramanujan' }
_.xorWith(objects, [existingObject], _.isEqual)
// returns [ { id: 2, username: 'bill' }, { id: 2, username: 'ted' } ]
_.xorWith(objects, [newObject], _.isEqual)
// returns [ { id: 1, username: 'fred' }, { id: 2, username: 'bill' }, { id: 2, username: 'ted' } ,{ id: 1729, username: 'Ramanujan' } ]
试试这个
第一种方法使用一些
let arr = [{ id: 1, username: 'fred' }, { id: 2, username: 'bill' }, { id: 3, username: 'ted' }];
let found = arr.some(ele => ele.username === 'bill');
console.log(found)
第二种方法使用包括、映射
let arr = [{ id: 1, username: 'fred' }, { id: 2, username: 'bill' }, { id: 3, username: 'ted' }];
let mapped = arr.map(ele => ele.username);
let found = mapped.includes('bill');
console.log(found)
const __checkIfElementExists__ = __itemFromArray__ => __itemFromArray__.*sameKey* === __outsideObject__.*samekey*;
if (cartArray.some(checkIfElementExists)) {
console.log('already exists');
} else {
alert('does not exists here')
