Adding pad spacing to string within javascript

Question

I have an application that is sending a variable to another system which requires the variable to be 16 characters. However, the user is not required to enter a 16 digit number.

Here is the coding I have so far:

Within the file to activate the javascript:

<A HREF="javascript:onClick=creditlink()" title="Enter own credit memo number.">Create Credit Memo</a>

Here is the javascript I am using:

function creditlink ()
{
var cmnum2 = document.getElementById('creditmemo').value;
var cmnum = document.getElementById('autocmnum').value;
var clmid = document.getElementById('claimid').value;
//alert (cmnum);
if (cmnum2) {


window.open("https://somewebpage.cfm?creditmemos=" + cmnum2 + "&claimid=" +clmid );
}
//This is the customer did not want to enter their own number one would be auto generated
else {

window.open("https://somewebpage.cfm?creditmemos=" + cmnum + "&claimid=" +clmid );

}

}

So here where I need help for cmnum2 I need it to be turned into 16 characters before it is sent in the link. FYI this function is working great.

So my thought was to just add space padding before the value to equal 16characters. Here is a example of what I need:

User enter: cmnum2 = "61150331" (8 characters) New value: cmnum2 = "(8 spaces)61150331" (total 16 characters with spaces)

I believe I have seen it done with functions like string.format or string padleft or padright but I am not sure how the coding format would work to make it 16 no matter what the value is.

Yes, is it Java or Javascript? I'm assuming javascript, by the code. — Xynariz
– Xynariz, Commented Aug 29, 2013 at 20:27

Xotic750 · Accepted Answer · 2013-08-29 21:54:25Z

Here is an example that uses ES6 (Harmony) functions, String.prototype.repeat. I've included the polyfils for you, or you could use ES6 shim. Anyway, this is just a further example of what can be done, and what will become standard.

Javascript

// ES6 - Harmony polyfils
if (typeof Math.sign !== "function") {
    Math.sign = function (n) {
        if (n < 0) {
            return -1;
        }

        return 1;
    };
}

if (typeof Number.toInteger !== "function") {
    Number.toInteger = function (value) {
        var n = +value;

        if (isNaN(n)) {
            return +0;
        }

        if (n === 0 || !isFinite(n)) {
            return n;
        }

        return Math.sign(n) * Math.floor(Math.abs(n));
    }
}

if (typeof String.prototype.repeat !== "function") {
    String.prototype.repeat = (function () {
        var repeat = function (s, times) {
            if (times < 1) {
                return "";
            }

            if (times % 2) {
                return repeat(s, times - 1) + s;
            }

            var half = repeat(s, times / 2);

            return half + half;
        };

        return function (times) {
            times = Number.toInteger(times);
            if (times < 0 || times === Infinity) {
                throw new RangeError();
            }

            return repeat(String(this), times);
        };
    }());
}

// Helper function
function clamp(num, min, max) {
    return Math.min(Math.max(num, min), max);
};

// The padding function
function pad(userString) {
    return " ".repeat(clamp(16 - userString.length, 0, 16)) + userString;
}

// Example usage
var input = "12345",
    output = pad(input);

console.log(input, input.length, output, output.length);

Output

12345 5            12345 16

On jsfiddle

Xynariz · Accepted Answer · 2013-08-29 20:57:00Z

0

Here's one possible solution. Note that if the string is already 16 (or more) characters, the for loop will never be entered.

function padTo16Chars(string) {
    var length = string.length;
    var newString = "";
    for (var index = 0; index < (16 - length) ; index++) {
        newString = newString + " ";
    }
    string = newString + string;
}

For this to work, put a call to this method inside your creditlink method, like so:

function creditlink ()
{
    var cmnum2 = document.getElementById('creditmemo').value;
    padTo16Chars(cmnum2);
    //Other stuff
}

EDIT: The padding was after the value, now it's before.

edited Aug 29, 2013 at 20:57

answered Aug 29, 2013 at 20:36

Xynariz

1,2431 gold badge11 silver badges28 bronze badges

Comments

Bryan · Accepted Answer · 2013-08-29 21:58:17Z

0

A simple way to accomplish this would be to use a while loop:

while (cmnum2.length < 16) {
   cmnum2 = " " + cnmun2
}

However you would probably want to place that within a function and return the new string with added spaces.

var cmnum2 = "09872";

var num = function(cmnum2){
    while (cmnum2.length < 16) {
      cmnum2 = " " + cmnum2;
    }
    return cmnum2;
};

console.log(num(cmnum2)); //"(11spaces)09872"

Hope that helps.

edited Aug 29, 2013 at 21:58

answered Aug 29, 2013 at 21:51

Bryan

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Comments

Sebas · Accepted Answer · 2015-11-01 18:46:20Z

0

I really like Xotic750's answer. I had something else though:

/**
 * @description Pads given string 
 * @param {string} s The string to pad
 * @param {number} n The amount of spaces to pad
 * @returns {string} Left padded string.
 * @todo check parameters' types and allowed values, undefined, etc.
 */
function padLeft(s,n) {
    return ((s.length >= n) ? s : (new Array(n - s.length)).join(" ") + s);
}

It's a pretty straightforward solution...

answered Nov 1, 2015 at 18:46

Sebas

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1 Comment

Arnaud Denoyelle Over a year ago

Thank you. I used that in my code. I think that there is a little bug here : new Array(n - s.length). It should be new Array(n - s.length + 1).

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