如何格式化输入类型编号？

Question

当输入为number类型时，我在格式化数字时遇到问题。我想要的是，当用户在字段中键入一些数字时，它应该是1000 -> 1,000。这是我的代码示例：

  import { Pipe, PipeTransform } from '@angular/core';

@Pipe({
    name: 'numberFormat',
})
export class NumberFormatPipe implements PipeTransform {

    transform(val) {
        if (val) {
            val = this.format_number(val, '');
        }
        return val;
    }

    format_number(number, prefix) {
        console.log('Value: ', number);
        const thousand_separator = ',';
        const decimal_separator = '.';
        const regex = new RegExp('[^' + decimal_separator + '\\d]', 'g');
        const number_string = String(number);
        String(number_string).replace(regex, '').toString;
        const split = number_string.split(decimal_separator);
        const rest = split[0].length % 3;
        let result = split[0].substr(0, rest);
        const thousands = split[0].substr(rest).match(/\d{3}/g);

        if (thousands) {
            const separator = rest ? thousand_separator : '';
            result += separator + thousands.join(thousand_separator);
        }
        result = split[1] !== undefined ? result + decimal_separator + split[1] : result;
        return prefix === undefined ? result : (result ? prefix + result : '');
    }
}