Normalize file size description

size_normalize.js

/**
 * @author huzemin8 <huzemin8@126.com>
 */
 
 
/**
 * @param in_size mixed  file size
 * @param type string output size
 * @param precision int
 * @return string
 */
function size_normalize(in_size, type, precision) {
    var size = '', byte = 0;
    var p = /^\s*(\d+)\s?(\w+)?\s?/;
    // 精度
    if(precision == undefined) {
        precision = 2;
    }
    if(type !== undefined) {
        type = type.toUpperCase();
    } else {
        type = 'B';
    }

    if(isNaN(in_size)) {
        var in_type = '';
        var match = in_size.match(p);
        if(match) {
            byte = parseFloat(match[1]);
            if(match[2] != undefined) {
                var toByte = {
                    'bits' : 8,
                    'b' : 1,
                    'kb' : 1024,
                    'mb' : 1024 * 1024,
                    'GB' : 1024 * 1024 * 1024
                };
                in_type = match[2].toLowerCase();
                if(toByte[in_type] != undefined) {
                    byte = byte * toByte[in_type];
                }
            }
        } else {
            throw new Error('Unrecognized size');
        }
    } else {
        byte = in_size;
    }

    switch(type) {
        case 'B':
            size = byte + type;
            break;
        case 'KB':
            size = (byte / 1024).toFixed(precision) + type;
            break;
        case 'MB':
            size = (byte / 1024 / 1024).toFixed(precision) + type;
            break;
        case 'GB':
            size = (byte / 1024 / 1024 / 1024).toFixed(precision) + type;
            break;
        default:
            size = byte * 8 + 'bits'
    }
    return size;
}