How can I convert this short PHP function into Javascript? [closed]

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Closed 6 years ago.

How can I replicate this PHP code into Javascript ?? It takes a number like 2-9999 (serial number) and converts it into a NUMBER ... 2-999 would be a different value when converted.

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;
}

I added a dependency function below

// dependency function
    /*****************************************************************************
    * CHECKS IF A STRING REPRESENTS A NUMBER
    ******************************************************************************/
    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;
    }

回答1:

php syntax is pretty similar to JS.

Just take the variables and remove the $, and declare them with the var keyword.

function esn_to_num(esn) {
    var tmp = [];
    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;
}

Then you need to replace all your php functions with equivalent JS ones. Look up "javascript equivalents of explode, sizeof.

Follow the same process to rewrite my_isnum in javascript (clearly not a native php function).

edit: after seeing your update, I realize there is probably already a good chunk of code on Stack Overflow (or elsewhere) which will what my_isnum does. Either search "js function to determine if string is number" or ask that in a seperate question here.

You can do all this in chromes javascript console, and keep iterating until you stop getting errors. If you run into a specific problem and are stuck, thats a good point to ask about it on Stack Overflow.

来源：https://stackoverflow.com/questions/14656412/how-can-i-convert-this-short-php-function-into-javascript