yii\i18n\Formatter::asSize PHP Method

    public function asSize($value, $decimals = null, $options = [], $textOptions = [])
    {
        if ($value === null) {
            return $this->nullDisplay;
        }
        list($params, $position) = $this->formatSizeNumber($value, $decimals, $options, $textOptions);
        if ($this->sizeFormatBase == 1024) {
            switch ($position) {
                case 0:
                    return Yii::t('yii', '{nFormatted} {n, plural, =1{byte} other{bytes}}', $params, $this->locale);
                case 1:
                    return Yii::t('yii', '{nFormatted} {n, plural, =1{kibibyte} other{kibibytes}}', $params, $this->locale);
                case 2:
                    return Yii::t('yii', '{nFormatted} {n, plural, =1{mebibyte} other{mebibytes}}', $params, $this->locale);
                case 3:
                    return Yii::t('yii', '{nFormatted} {n, plural, =1{gibibyte} other{gibibytes}}', $params, $this->locale);
                case 4:
                    return Yii::t('yii', '{nFormatted} {n, plural, =1{tebibyte} other{tebibytes}}', $params, $this->locale);
                default:
                    return Yii::t('yii', '{nFormatted} {n, plural, =1{pebibyte} other{pebibytes}}', $params, $this->locale);
            }
        } else {
            switch ($position) {
                case 0:
                    return Yii::t('yii', '{nFormatted} {n, plural, =1{byte} other{bytes}}', $params, $this->locale);
                case 1:
                    return Yii::t('yii', '{nFormatted} {n, plural, =1{kilobyte} other{kilobytes}}', $params, $this->locale);
                case 2:
                    return Yii::t('yii', '{nFormatted} {n, plural, =1{megabyte} other{megabytes}}', $params, $this->locale);
                case 3:
                    return Yii::t('yii', '{nFormatted} {n, plural, =1{gigabyte} other{gigabytes}}', $params, $this->locale);
                case 4:
                    return Yii::t('yii', '{nFormatted} {n, plural, =1{terabyte} other{terabytes}}', $params, $this->locale);
                default:
                    return Yii::t('yii', '{nFormatted} {n, plural, =1{petabyte} other{petabytes}}', $params, $this->locale);
            }
        }
    }

 /**
  * https://github.com/yiisoft/yii2/issues/4960
  */
 public function testAsSizeConfiguration()
 {
     $this->assertSame("1023 bytes", $this->formatter->asSize(1023));
     $this->assertSame("1023 B", $this->formatter->asShortSize(1023));
     $this->formatter->thousandSeparator = '.';
     $this->assertSame("1023 bytes", $this->formatter->asSize(1023));
     $this->assertSame("1023 B", $this->formatter->asShortSize(1023));
 }