typescript 如何在TypeScript中检查对象是否具有属性并且属性值是否为真
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How to check if object has property and property value is true in TypeScript
提问by LearnToday
I want to check if the following object has the property forumsand if that property value is true.
我想检查以下对象是否具有该属性forums以及该属性值是否为true.
{forums: true, pages: true, photos: true, videos: true}
I am using TypeScript Angular 5.
我正在使用 TypeScript Angular 5。
I do this for now and works fine.
我现在这样做并且工作正常。
let item = 'forums';
if ( this.itemsmodel.hasOwnProperty(item) ) {
//Which is true.
if (this.itemsmodel[item]) {
item = item;
} else {
item = 'pages';
}
}
Is there an Angular way or TypeScript way for this?
是否有 Angular 方式或 TypeScript 方式？
回答by Vivek Doshi
Shortest way ,this will check both by default :
最短的方法，这将默认检查两个：
if(this.itemsmodel[item])
First it will try to fetch this.itemsmodelof itemif there is not then it will return undefinedand if it's found then it will return value,
首先它会尝试获取this.itemsmodel，item如果没有则返回undefined，如果找到则返回值，
Same but long way of doing :
相同但很长的路要走：
if(this.itemsmodel[item] && this.itemsmodel[item] === true)
Here first will check if key exists , second will check for the value
这里首先将检查键是否存在，第二个将检查值
As result you can convert your code to something like this :
因此，您可以将代码转换为这样的：
let item = 'forums';
if (this.itemsmodel[item]) {
item = item;
} else {
item = 'pages';
}
