Javascript code to convert serial numbers converted from PHP

Question

These two Javascript functions are supposed to convert serial numbers (2-9999) for example into a number , but the functions below are not working for some reason .. they were originally written in PHP ... Works in PHP but not for Javascript.

<html>
<head>
<script type="text/javascript">

    function my_isnum(str, negative=false, decimal=false)
{
    var has_decimal = false;
    var len = strlen(str);
    if (len > 0) {
        var valid = true;
        for (var i=0; valid && i < len; i++) {
            if (!(str[i] >= "0" && str[i] <= "9")) {
                if (str[i] == "-") {
                    if (!negative || i != 0) {
                        valid = false;
                    }
                } else if (str[i] == ".") {
                    if (!decimal || has_decimal) {
                        valid = false;
                    }
                } else {
                    valid = false;
                }
            }
        }
    } else {
        valid = false;
    }
    return valid;
}

function esn_to_num(esn) {
    var tmp = [];
    if ((tmp = esn.split("-")) {
        if (tmp.length == 2
            && my_isnum(tmp[0])
            && my_isnum(tmp[1])
        ) {
            esn = ((tmp[0] << 23) | tmp[1]);
        } else {
            esn = -1;
        }
    } else {
        esn = -1;
    }
    return esn;
}

alert(2-9999);

</script> </head>
</html>

Original PHP functions

<?php
function my_isnum($str, $negative=false, $decimal=false)
{
    $has_decimal = false;
    $len = strlen($str);
    if ($len > 0) {
        $valid = true;
        for ($i=0; $valid && $i<$len; $i++) {
            if (!($str[$i] >= '0' && $str[$i] <= '9')) {
                if ($str[$i] == '-') {
                    if (!$negative || $i != 0) {
                        $valid = false;
                    }
                } else if ($str[$i] == '.') {
                    if (!$decimal || $has_decimal) {
                        $valid = false;
                    }
                } else {
                    $valid = false;
                }
            }
        }
    } else {
        $valid = false;
    }
    return $valid;
}

function esn_to_num($esn)
{

    if (($tmp = explode('-', $esn))) {

        if (sizeof($tmp) == 2
            && my_isnum($tmp[0])
            && my_isnum($tmp[1])
        ) {
            $esn = (($tmp[0] << 23) | $tmp[1]);
        } else {
            $esn = -1;
        }
    } else {
        $esn = -1;
    }

    return $esn;
}




?>

Why don't you use something like ParseFloat ?

Benjamin Toueg
– Benjamin Toueg

2013-02-01 23:37:01 +00:00
Commented Feb 1, 2013 at 23:37 — Benjamin Toueg
– Benjamin Toueg, Commented Feb 1, 2013 at 23:37
Didn't you like the answers here and here?

bfavaretto
– bfavaretto

2013-02-01 23:42:09 +00:00
Commented Feb 1, 2013 at 23:42 — bfavaretto
– bfavaretto, Commented Feb 1, 2013 at 23:42

Robin Kanters · Accepted Answer · 2013-02-01 23:50:48Z

4

There is no such thing as strlen in Javascript. Use str.length instead.

Also, as Jason Sperske suggested below, change this:

function my_isnum(str, negative=false, decimal=false)

To this:

function my_isnum(str, negative, decimal)
{
    if (typeof negative == "undefined") negative = false;
    if (typeof decimal == "undefined") decimal = false;
    ....
}

edited Feb 1, 2013 at 23:50

answered Feb 1, 2013 at 23:37

Robin Kanters

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13 Comments

Jason Sperske Over a year ago

Also, function my_isnum(str, negative=false decimal=false) is not valid JavaScript

Robin Kanters Over a year ago

Yeah I was looking at that after I posted the answer, but indeed! (For anyone who doesn't see it: missing comma between false and decimal )

Jason Sperske Over a year ago

Sorry the mistake is larger than that, functions in JavaScript don't have default values like that

Robin Kanters Over a year ago

I KNEW IT! I didn't know for sure, so I looked it up, and the first page I opened said it did... Stupid me for not looking further than that. Internet mistake #1...

Jason Sperske Over a year ago

Wait wait wait... jsfiddle.net/M9KTN JabaScript is currently blowing my mind, what am I not understanding here?

|

Mike Samuel · Accepted Answer · 2013-02-02 01:05:47Z

3

These two javascript functions are supposed to convert serial numbers (2-9999) for example into a number.

Why not just get rid of the - and parse as a decimal number?

function padToFourDigits(_, digits) {
  return "0000".substring(digits.length) + digits;
}

function serialToNum(serialNumStr) {
  return +(serialNumStr.replace(/-(\d{1,4})/g, padToFourDigits));
}

Then

serialToNum('2-9999') === 29999

serialToNum('2-999')  === 20999

edited Feb 2, 2013 at 1:05

answered Feb 1, 2013 at 23:41

Mike Samuel

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3 Comments

bfavaretto Over a year ago

Yes, the OP got this advice earlier, but for some reason decided not to take it.

JBa Over a year ago

@Mike .. It's an assignment .. I wish I could just do it like that

Mike Brant Over a year ago

@JBa Did the assignment tell you to do a line for line port of the code or just implement the same functionality in javascript? Personally if I had giving this assignment and you returned with the answer above I would think very highly of it, as you would have greatly simplified the code.

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