javascript - 如何以 Angular 8 显示转换后的值？

Question

在我的项目中，我将 .net core 2.2 用于后端，将 angular 8 用于前端。场景是我在后端有一些具有一定范围的整数值。例如:

    [Required]
    [Range(1073741824, 1099511627776)] // 1GB -> 1TB
    public long DiskSize { get; set; }

为了显示值，我正在使用 ng-slider5我的 typescript 文件如下所示:

diskOptions: Options = {
    floor: 1073741824,
    ceil: 1099511627776
  };

我的 html 文件如下所示:

 <div class="input-group mt-1">
      <div class="input-group-prepend">
        <div class="input-group-text">
          <i class="fas fa-hdd text-primary"></i>&nbsp;Disk Size
        </div>
      </div>     
        <ng5-slider [(value)]="model.diskSize" name="diskSize" [(ngModel)]="model.diskSize" 
     [options]="diskOptions" class="form-control"></ng5-slider>
    </div>

我想在 slider 中实现，显示的不是值而是 1gb 递增 1gb 直到 1tb。1024gb 时也显示 gb 并更改 tb。 slider 看起来像:

Answer 1

我从这个 repository 找到了这个管道.尝试在您的 Angular 应用程序中实现它。

bytes.pipe.ts

import { Pipe, PipeTransform, NgModule } from '@angular/core';
import { isNumberFinite, isPositive, isInteger, toDecimal } from '../utils/utils';

export type ByteUnit = 'B' | 'kB' | 'KB' | 'MB' | 'GB' | 'TB';

@Pipe({
  name: 'bytes',
})
export class BytesPipe implements PipeTransform {
  static formats: { [key: string]: { max: number; prev?: ByteUnit } } = {
    B: { max: 1024 },
    kB: { max: Math.pow(1024, 2), prev: 'B' },
    KB: { max: Math.pow(1024, 2), prev: 'B' }, // Backward compatible
    MB: { max: Math.pow(1024, 3), prev: 'kB' },
    GB: { max: Math.pow(1024, 4), prev: 'MB' },
    TB: { max: Number.MAX_SAFE_INTEGER, prev: 'GB' },
  };

  transform(input: any, decimal: number = 0, from: ByteUnit = 'B', to?: ByteUnit): any {
    if (!(isNumberFinite(input) && isNumberFinite(decimal) && isInteger(decimal) && isPositive(decimal))) {
      return input;
    }

    let bytes = input;
    let unit = from;
    while (unit !== 'B') {
      bytes *= 1024;
      unit = BytesPipe.formats[unit].prev!;
    }

    if (to) {
      const format = BytesPipe.formats[to];

      const result = toDecimal(BytesPipe.calculateResult(format, bytes), decimal);

      return BytesPipe.formatResult(result, to);
    }

    for (const key in BytesPipe.formats) {
      if (BytesPipe.formats.hasOwnProperty(key)) {
        const format = BytesPipe.formats[key];
        if (bytes < format.max) {
          const result = toDecimal(BytesPipe.calculateResult(format, bytes), decimal);

          return BytesPipe.formatResult(result, key);
        }
      }
    }
  }

  static formatResult(result: number, unit: string): string {
    return `${result} ${unit}`;
  }

  static calculateResult(format: { max: number; prev?: ByteUnit }, bytes: number) {
    const prev = format.prev ? BytesPipe.formats[format.prev] : undefined;
    return prev ? bytes / prev.max : bytes;
  }
}

@NgModule({
  declarations: [BytesPipe],
  exports: [BytesPipe],
})
export class NgBytesPipeModule {}

工具

export type CollectionPredicate = (item?: any, index?: number, collection?: any[]) => boolean;

export function isUndefined(value: any): value is undefined {
  return typeof value === 'undefined';
}

export function isNull(value: any): value is null {
  return value === null;
}

export function isNumber(value: any): value is number {
  return typeof value === 'number';
}

export function isNumberFinite(value: any): value is number {
  return isNumber(value) && isFinite(value);
}

// Not strict positive
export function isPositive(value: number): boolean {
  return value >= 0;
}

export function isInteger(value: number): boolean {
  // No rest, is an integer
  return value % 1 === 0;
}

export function isNil(value: any): value is null | undefined {
  return value === null || typeof value === 'undefined';
}

export function isString(value: any): value is string {
  return typeof value === 'string';
}

export function isObject(value: any): boolean {
  return value !== null && typeof value === 'object';
}

export function isArray(value: any): boolean {
  return Array.isArray(value);
}

export function isFunction(value: any): boolean {
  return typeof value === 'function';
}

export function toDecimal(value: number, decimal: number): number {
  return Math.round(value * Math.pow(10, decimal)) / Math.pow(10, decimal);
}

export function upperFirst(value: string): string {
  return value.slice(0, 1).toUpperCase() + value.slice(1);
}

export function createRound(method: string): Function {
  // <any>Math to suppress error
  const func: any = (<any>Math)[method];
  return function(value: number, precision: number = 0) {
    if (typeof value === 'string') {
      throw new TypeError('Rounding method needs a number');
    }

    if (typeof precision !== 'number' || isNaN(precision)) {
      precision = 0;
    }

    if (precision) {
      let pair = `${value}e`.split('e');
      const val = func(`${pair[0]}e` + (+pair[1] + precision));

      pair = `${val}e`.split('e');
      return +(pair[0] + 'e' + (+pair[1] - precision));
    }

    return func(value);
  };
}

export function leftPad(str: string, len: number = 0, ch: any = ' ') {
  str = String(str);
  ch = toString(ch);
  let i = -1;
  const length = len - str.length;

  while (++i < length && str.length + ch.length <= len) {
    str = ch + str;
  }

  return str;
}

export function rightPad(str: string, len: number = 0, ch: any = ' ') {
  str = String(str);
  ch = toString(ch);

  let i = -1;
  const length = len - str.length;

  while (++i < length && str.length + ch.length <= len) {
    str += ch;
  }

  return str;
}

export function toString(value: number | string) {
  return `${value}`;
}

export function pad(str: string, len: number = 0, ch: any = ' '): string {
  str = String(str);
  ch = toString(ch);
  let i = -1;
  const length = len - str.length;

  let left = true;
  while (++i < length) {
    const l = str.length + ch.length <= len ? str.length + ch.length : str.length + 1;

    if (left) {
      str = leftPad(str, l, ch);
    } else {
      str = rightPad(str, l, ch);
    }

    left = !left;
  }

  return str;
}

export function flatten(input: any[], index: number = 0): any[] {
  if (index >= input.length) {
    return input;
  }

  if (isArray(input[index])) {
    return flatten(input.slice(0, index).concat(input[index], input.slice(index + 1)), index);
  }

  return flatten(input, index + 1);
}

export function getProperty(value: { [key: string]: any }, key: string): any {
  if (isNil(value) || !isObject(value)) {
    return undefined;
  }

  const keys: string[] = key.split('.');
  let result: any = value[keys.shift()!];

  for (const key of keys) {
    if (isNil(result) || !isObject(result)) {
      return undefined;
    }

    result = result[key];
  }

  return result;
}

export function sum(input: Array<number>, initial = 0): number {
  return input.reduce((previous: number, current: number) => previous + current, initial);
}

// http://stackoverflow.com/questions/6274339/how-can-i-shuffle-an-array-in-javascript
export function shuffle(input: any): any {
  if (!isArray(input)) {
    return input;
  }

  const copy = [...input];

  for (let i = copy.length; i; --i) {
    const j = Math.floor(Math.random() * i);
    const x = copy[i - 1];
    copy[i - 1] = copy[j];
    copy[j] = x;
  }

  return copy;
}

export function deepIndexOf(collection: any[], value: any) {
  let index = -1;
  const length = collection.length;

  while (++index < length) {
    if (deepEqual(value, collection[index])) {
      return index;
    }
  }

  return -1;
}

export function deepEqual(a: any, b: any) {
  if (a === b) {
    return true;
  }

  if (!(typeof a === 'object' && typeof b === 'object')) {
    return a === b;
  }

  const keysA = Object.keys(a);
  const keysB = Object.keys(b);

  if (keysA.length !== keysB.length) {
    return false;
  }

  // Test for A's keys different from B.
  var hasOwn = Object.prototype.hasOwnProperty;
  for (let i = 0; i < keysA.length; i++) {
    const key = keysA[i];
    if (!hasOwn.call(b, keysA[i]) || !deepEqual(a[key], b[key])) {
      return false;
    }
  }

  return true;
}

export function isDeepObject(object: any) {
  return object.__isDeepObject__;
}

export function wrapDeep(object: any) {
  return new DeepWrapper(object);
}

export function unwrapDeep(object: any) {
  if (isDeepObject(object)) {
    return object.data;
  }

  return object;
}

export class DeepWrapper {
  public __isDeepObject__: boolean = true;

  constructor(public data: any) {}
}

export function count(input: any): any {
  if (!isArray(input) && !isObject(input) && !isString(input)) {
    return input;
  }

  if (isObject(input)) {
    return Object.keys(input).map(value => input[value]).length;
  }

  return input.length;
}

export function empty(input: any): any {
  if (!isArray(input)) {
    return input;
  }

  return input.length === 0;
}

export function every(input: any, predicate: CollectionPredicate) {
  if (!isArray(input) || !predicate) {
    return input;
  }

  let result = true;
  let i = -1;

  while (++i < input.length && result) {
    result = predicate(input[i], i, input);
  }

  return result;
}

export function takeUntil(input: any[], predicate: CollectionPredicate) {
  let i = -1;
  const result: any = [];
  while (++i < input.length && !predicate(input[i], i, input)) {
    result[i] = input[i];
  }

  return result;
}

export function takeWhile(input: any[], predicate: CollectionPredicate) {
  return takeUntil(input, (item: any, index: number, collection: any[]) => !predicate(item, index, collection));
}