问题描述
我正在尝试使用lodash迭代数组,但是有问题。
这是代码-
const items = [{
id: '1',name: 'A'
},{
id: '2',name: 'B'
},{
id: '3',name: 'C'
},{
id: '4',name: 'D'
},{
id: '5',name: 'E'
}]
var selectedItems = [0,1]
selectedValues = _.forEach(selectedItems,function(val) {
console.log('val -',val)
console.log('items[val] -',items[val].name)
return items[val].name
})
console.log('selectedValues - ',selectedValues)
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.20/lodash.min.js"></script>
我希望selectedValues应该包含值-'A'和'B'
解决方法
_.forEach
不会为赋值返回任何值,如果您想返回一个值,只需使用_.map
;
const items = [{
id: '1',name: 'A'
},{
id: '2',name: 'B'
},{
id: '3',name: 'C'
},{
id: '4',name: 'D'
},{
id: '5',name: 'E'
}]
var selectedItems = [0,1]
selectedValues = _.map(selectedItems,function(val){
console.log('val -',val)
console.log('items[val] -',items[val].name)
return items[val].name
})
console.log('selectedValues - ',selectedValues)
// [
// "A",// "B"
// ]
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.20/lodash.min.js"></script>
使用anonymous function,我们可以简化代码:
var selectedItems = [0,(val) => items[val].name);
console.log('selectedValues - ',selectedValues)
const items = [{id: '1',name: 'A'},{id: '2',name: 'B'},{id: '3',name: 'C'},{id: '4',name: 'D'},{id: '5',name: 'E'}]
var selectedItems = [0,// "B"
// ]
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.20/lodash.min.js"></script>
,
假设您要尝试抓住用户选择的那些对象,只需使用filter
和includes
就可以轻松完成lodash设置。
目前尚不清楚selectedItems
是索引还是ID。由于在这里ID是更好的用法(因为ID就是用于ID),因此我假设在下面的代码中
const items = [{
id: '1',name: 'A'
},{
id: '2',name: 'B'
},{
id: '3',name: 'C'
},{
id: '4',name: 'D'
},{
id: '5',name: 'E'
}]
var selectedItems = [0,1];
var selectedValues = _.filter(items,function(item) {
return _.includes(selectedItems,+item.id);
});
console.log('selectedValues - ',selectedValues);
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.20/lodash.min.js"></script>
但是,您也可以很轻松地做到这一点:
const items = [{
id: '1',name: 'E'
}];
const selectedItems = [0,1];
const selectedValues = items.filter( i => selectedItems.includes(+i.id));
console.log('selectedValues - ',selectedValues);