Question

我正在创建一个对象，然后将其转换为json。我有以下内容：

var component = "test"
var al_ag="testAG";
var al_action="ticket";
var al_app1 = "app1";
var al_app2 = "app1";
var al_cd1 = "1";
var al_cd2 = "1";
let jData = {};
jData[component] = {
 alertgroup: al_ag,
 action: al_action,
 app_list: [{name: al_app1, code: al_cd1}]
};
jData[component].app_list.push({name: al_app2, code: al_cd2});
console.log(JSON.stringify(jData, null, '\t'));

JSON.stringify（jData）将app_list列出为两个项目的数组。

.
"app_list": [
            {
                "name": "app1",
                "code": "1"
            },
            {
                "name": "app2",
                "code": "2"
            }
        ]
.

在执行app_list.{name: al_app2, code: al_cd2}之前，我如何检查app1是否已经存在而不能推送是否已经存在。

Answer 1

下面是一个对{em> app2 和 app3 对象使用filter的示例。请注意，没有重复项。

let app_list = [
      {
          "name": "app1",
          "code": "1"
      },
      {
          "name": "app2",
          "code": "2"
      }
  ]

// Check app2 doesn't already exist in array
if (app_list.filter(a => a.name === "app2").length === 0) {
  app_list.push({ name: "app2", "code": 2 });
}

// Check app3 doesn't already exist in array
if (app_list.filter(a => a.name === "app3").length === 0) {
  app_list.push({ name: "app3", "code": 3 });
}

console.log(app_list);

Answer 2

您可以简单地使用! array.some（）来检查元素is not是否已经存在

let component = "test"
  , al_ag     = "testAG"
  , al_action = "ticket"
  , al_app1   = "app1"
  , al_app2   = "app1"
  , al_cd1    = "1"
  , al_cd2    = "1"
  , jData     = {}
;

jData[component] = { alertgroup: al_ag
                   , action: al_action
                   , app_list: [{ name: al_app1, code: al_cd1 }]
                   };

let newOne = { name: al_app2, code: al_cd2 }

if (!jData[component].app_list.some(el=>el.name===newOne.name && el.code===newOne.code)  )
  {
  jData[component].app_list.push(newOne);
  }

console.log(JSON.stringify(jData, null, 2));

doc => https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/some

Answer 3

我只是根据您的代码添加了一些代码。然后使用findIndex检查app1上是否存在app_list。如果索引为-1，则表示列表中不存在app1。

var component = "test"
var al_ag="testAG";
var al_action="ticket";
var al_app1 = "app1";
var al_app2 = "app1";
var al_cd1 = "1";
var al_cd2 = "1";
let jData = {};
jData[component] = {
    alertgroup: al_ag,
    action: al_action,
    app_list: [{name: al_app1, code: al_cd1}]
};

// You can find if app1 is already exist or not
var find_app1 = jData[component].app_list.findIndex(data => data.name === 'app1');

// If the data already exist then push app2
if (find_app1 > -1) {
    console.log('app1 Exist')
    jData[component].app_list.push({name: al_app2, code: al_cd2});
} else {
    console.log('app1 is not Exist')
}
console.log(JSON.stringify(jData, null, '\t'));

Javascript：检查项目是否存在于对象内的数组中

3 个答案: