我有一个数组对象调用listOfObjects。
[{"name":"A", "data":"[{"value1":"1","value2":"2"}]"},
{"name":"B", "data":"[{"value1":"1","value2":"2"}]"}]
我想做的是将一个对象插入到数组为空的数组中。如果数组不为空,则检查其中的项。如果项目已经存在,请更新该项目,否则将其添加到数组中。下面是我的代码
var searchName= "A";
if (listOfObjects.length > 0) {
for (var i = 0; i < listOfObjects.length; i++) {
if (listOfObjects[i].name == searchName) {
listOfObjects[i].data = data;
break;
} else {
insert = {
'name': searchName,
'data': data
};
listOfObjects.push(insert);
}
}
} else {
insert = {
'name': searchName,
'data': data
};
listOfObjects.push(insert);
}
当我运行它时,即使 A 已经存在,它也会更新现有项目,但也会在对象列表中再添加一个时间。有没有办法实现我想要的?谢谢。。
问题是您正在插入for
循环内的数组中寻找匹配项。相反,请记住您是否看到过匹配项,如果没有,请在循环后插入。也没有理由进行length
检查,也没有理由重复插入逻辑:
var searchName= "A";
var found = false;
for (var i = 0; !found && i < listOfObjects.length; i++) {
if (listOfObjects[i].name == searchName) {
listOfObjects[i].data = data;
found = true;
}
}
if (!found) {
listOfObjects.push({
'name': searchName,
'data': data
});
}
请注意,如果您愿意,可以使用Array#find
(可以为旧浏览器进行多填充(来查找条目,而不是for
循环:
var searchName= "A";
var entry = listOfObjects.find(function(entry) {
return entry.name == searchName;
});
if (entry) {
entry.data = data;
} else {
listOfObjects.push({
'name': searchName,
'data': data
});
}
首先更改此内容
[{"name":"A", "data":"[{"value1":"1","value2":"2"}]"},
{"name":"B", "data":"[{"value1":"1","value2":"2"}]"}]
由
[{"name":"A", "data":[{"value1":1,"value2":2}]},
{"name":"B", "data":[{"value1":"1","value2":"2"}]}];
因为您的列表会throw Uncaught SyntaxError: Unexpected identifier
编写另一个简单的函数来获取具有选定搜索名称的项目列表对象[i]。在这里,'getSearchObject((' 函数检查 searchName 是否存在,然后添加或更新数组。
addOrRemoveItem() {
let listOfObjects = [
{ "name": "A", "data": "[{'value1':'1','value2':'2'}]" },
{ "name": "B", "data": "[{'value1':'1','value2':'2'}]" }
],
data = '[{"value1":"1","value2":"2"}]';
var searchName = "C";
if (listOfObjects.length > 0) {
let searchObj = this.getSearchObject(listOfObjects, searchName);
if (searchObj) {
searchObj.data = data;
} else {
let insert = {
"name": searchName,
"data": data
}
listOfObjects.push(insert);
}
} else {
let insert = {
"name": searchName,
"data": data
}
listOfObjects.push(insert);
}
}
getSearchObject(objArr, searchKey) {
var obj = null;
for (let i = 0; i < objArr.length; i++) {
if (objArr[i].name === searchKey) {
obj = objArr[i];
}
}
return obj;
}
一个通用解决方案,可以识别较旧的 JS 引擎(filter
而不是 find
(,但总是假设传递唯一项目列表可以像这样实现......
function updateList(itemList, item) { // - always assume a list of unique items.
var
itemName = item.name,
listItem = itemList.filter(function (elm) { // - assume `filter`, not find`.
return (elm.name === itemName); // - find/get existing list item by name.
})[0];
if (listItem) {
listItem.data = item.data;
} else {
itemList.push(item)
}
}
var list = [
{ "name": "A", "data": [ { "value1": "A1", "value2": "A2" }] },
{ "name": "B", "data": [ { "value1": "B1", "value2": "B2" }] },
{ "name": "C", "data": [ { "value1": "C1", "value2": "C2" }] }
];
console.log('list : ', list);
updateList(list, { "name": "D", "data": [ { "value1": "D1", "value2": "D2" }] });
updateList(list, { "name": "B", "data": [ { "value1": "b_1", "value2": "b_2", "value3": "b_3" }] });
updateList(list, { "name": "C", "data": [ { "value3": "C3" }] });
console.log('list : ', list);
.as-console-wrapper { max-height: 100%!important; top: 0; }