我有三个组件:GalleryAddComponent添加一个新元素,GalleryItemComponent编辑元素,FieldsComponent我想在组件中使用的表单:GalleryAddComponent和GalleryItemComponent.所有组件都在里面GalleryComponent.但是当我去组件GalleryAddComponent添加一个新元素时,我得到错误:ERROR TypeError: Cannot read property 'controls' of undefined.也在组件中:GalleryItemComponent.
帮助解决此问题,以便编辑和添加逻辑正常工作.
GalleryAddComponent的模板
<div class="card">
<div class="card-body">
<form [formGroup]="angForm" novalidate>
<app-fields [formGroup]="angForm"></app-fields>
<div class="form-group but-group">
<button (click)="addPost(title.value, url.value); angForm.reset(title.value, url.value)"
[disabled]="angForm.pristine || angForm.invalid"
class="btn btn-primary">Add
</button>
<a routerLink="/" class="btn btn-danger">Back</a>
</div>
</form>
</div>
</div>GalleryAddComponent的代码
export class GalleryAddComponent implements OnInit {
angForm: FormGroup;
isAdded: boolean = false;
constructor(private fb: FormBuilder, private galleryService: GalleryService) {}
ngOnInit() …如何实现用于乘以任意数量的数字的锁定功能。
调用示例：
multiply(1)(2)(3)(4)(5) // 120
为了完成这个任务，需要重新定义toString内部函数的方法，该方法应该返回累积结果，但我有结果NaN。
multiply(1)(2)(3)(4)(5) // 120
"武器"如何实现方法"toString",这对于Object.keys()是不可用的.
function Weapon(name,damage) {
this.name = name;
this.damage = damage;
this.toString = function () {
return this.name + this.damage + " damage";
}
}
var bow = new Weapon(' Golden bow, ',20);
var sword = new Weapon(' Magic sword, ', 40);
console.log(bow.toString());
console.log(sword.toString());
Object.defineProperty(Weapon, "toString", {enumerable: false});在该sortProductsByPrice (sortOrder)方法中,当我删除或添加新产品时,排序不起作用,排序仅适用于this.products默认情况下阵列中的产品.
(产品按点击排序<th> Price: </ th>).
在移除/添加货物之后,分类也必须使用.
//Product Creation Class
class Product {
constructor(name, count, price) {
this.name = name;
this.count = count;
this.price = price;
}
}
Product.SORT_ORDER_ASC = 1;
Product.SORT_ORDER_DESC = -1;
// ?lass where products are recorded
class Shop {
constructor() {
this.products = [];
}
//method for adding a product
addProduct(newProduct) {
this.products.push(newProduct);
}
//method for remove product by name
deleteProductByName(productName) {
let i = this.products.length;
while (i--) {
if …我想在显示来自使用MatSnackBar. （材料模块在应用程序的模块中导入）。
但是，默认的小吃店不支持图标。我如何实现这样的功能？
import { Injectable } from '@angular/core'
import {MatSnackBar} from '@angular/material/snack-bar';
import {MatSnackBarHorizontalPosition, MatSnackBarVerticalPosition} from "@angular/material";
@Injectable()
export class MessagesService {
horizontalPosition: MatSnackBarHorizontalPosition = 'right';
verticalPosition: MatSnackBarVerticalPosition = 'top';
constructor(private snackBar: MatSnackBar) {
}
info(message: string) {
const icon = `<mat-icon>info</mat-icon>`;
const msg = `${icon} ${message}`;
this.snackBar.open(msg, 'X', {
duration: 2000,
horizontalPosition: this.horizontalPosition,
verticalPosition: this.verticalPosition,
panelClass: ['info-message']
});
}
}
我实现了一种根据指定选项过滤商品的方法。该方法以包含搜索参数的选项对象作为参数，例如：{name: "item 2", Price: "<= 1000", count: "> 2"}，每个选项都是可选的。该方法必须返回带有商品的过滤数组。filterProductBy（选项）。\n我设法按名称过滤。告诉我如何正确地按数字过滤，以便过滤器调用如下所示：
\n\nconsole.log(shop.filterProductBy({\nname: "product 1",\ncount: ">1",\nprice: "<=1000"}));\n“计数”和“价格”需要与比较运算符一起解析，比较运算符设置过滤器的范围，这里有一个可以做到这一点的函数，我如何在我的方法中实现这个函数，一切都会工作？
\n\nconsole.log(shop.filterProductBy({\nname: "product 1",\ncount: ">1",\nprice: "<=1000"}));\n所有代码：
\n\nfunction parseCompOperator(oString, lhs) {\r\n if (oString.match("(?:<|>)=?\\\\d+") === null) {\r\n return "Invalid input";\r\n }\r\n\r\n let rator = oString.match("(?:<|>)=?")[0];\r\n let rhs = oString.match("\\\\d+")[0] * 1;\r\n\r\n if (rator === \'>\') {\r\n return (lhs > rhs);\r\n }\r\n else if (rator === \'<\') {\r\n return (lhs < rhs);\r\n }\r\n else if …javascript ×5
angular ×2
typescript ×2
arrays ×1
closures ×1
dom ×1
ecmascript-6 ×1
html ×1
sorting ×1
validation ×1