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Javascript Math.log() help wanted

World!
I'm trying to create a program in Javascript that takes the log of a number typed into an HTML input. Unfortunately i've encountered a problem where it wont accept the string with the .replace().
Its Function:
I.E: When log(10) is calculated, the function should first remove the first 4 char's "log(" next remove the last parenthesis ")" and then take the log of the no. between.
HTML includes style elements, button and input form and an output < DIV >.
//Function
function calculate()
{
var inputString = document.getElementById("inpstr");
var output = document.getElementById("output");
//TESTING CODE
/*
if (inputString.value.startsWith("log(").endsWith(")"))
{
console.log(output.innerHTML = inputString.value.substring(4, 20).replace(")", ""));
}
else
{
output.innerHTML = "false";
}
*/
//Math.log() calc *****DOESNT WORK*****
if (inputString.value.startsWith("log(").endsWith(")"))
{
output.innerHTML = Math.log(inputString.value.replace(")", "").substring(4, 20));
}
else
{
output.innerHTML = inputString.value;
}
event.preventDefault();
}
If someone can give me an effective solution that would be much appreciated.
Thanks,
Syntax

Since Math.log() accepts only number values and you're trying to pass a string to it, you should first parse this value into a float number and then pass it to the log function:
let val = parseFloat(inputString.value.replace(")", "").substring(4, 20));
output.innerHTML = Math.log(val);

I'm guessing I got downvoted for being lazy, so here is the quick info. Gonras got it right relating to what you want to extract, but he forgot to check that what's being input is actually a log.
That's where the regex below comes in handy! I'm matching the field to:
^ start of word, since we want to match the entire field.
log(
([-.\d])) any consecutive sequence () of numbers (\d), -, and '.', represented by the []. The \(...\) makes sure to save this inner part for later.
$ is end of word, see 1.
res will be null if there is no match. Otherwise, res[0] is the entire match (so the entire input field) and res[1] is the first 'capture group', at point 3 - which is presumably the number.
This of course fails for multiple "-" inside, or "." etc... so think it over.
//Function
function calculate()
{
var inputString = document.getElementById("inpstr");
var output = document.getElementById("output");
var res = /^log\(([-.\d]*)\)$/.exec(inputString.value);
if (res)
output.innerHTML = Math.log(res[1]);
else
output.innerHTML = res;
}
document.getElementById("output").innerHTML='start';
calculate()
<div id='output'></div>
<input id='inpstr' value='log(2.71828)'></input>
If I wanted to fix your if to supplement Gonras's solution:
if (inputString.value.startsWith("log(") && inputString.value.endsWith(")"))
Yours fails since startsWith() returns a boolean, which obviously doesn't have a endsWith function.

How to extract a specific text from a string. The hard part is the desired text changes periodically

I have an HTML document which contains this text somewhere in it
function deleteFolder() {
var mailbox = "CN=John Urban,OU=Sect-1,DC=TestServer ,DC=acme,DC=com";
var path = "/Inbox/";
//string of interest: "CN=John Urban,OU=Sect-1,DC=TestServer ,DC=acme,DC=com"
I just want to extract this text and store it in a variable in C#. My problem is that string of interest will slightly change each time the page is loaded, something like this:
"CN=John Urban,OU=Sect-1,DC=TestServer ,DC=acme,DC=com"
"CN=Jane Doe,OU=Sect-1,DC=TestServer ,DC=acme,DC=com"
etc....
How do I extract that ever changing string, without regular expression?

Is it always a function deleteFolder() which has its first line as var mailbox = "somestring"? And you are interested in somestring?
Based on the requirements you told us, could just search your string containing the HTML for var mailbox =" and then the next " and take all text between these two occurrences.
var htmlstring= "..."; //
var i1 = htmlstring.IndexOf("var mailbox = \"");
var i2 = i1 >= 0 ? htmlstring.IndexOf("\"", i1+15) : -1;
var result = i2 >= 0 ? htmlstring.Substring(i1+15, i2-(i1+15)): "not found";
VERY, VERY ugly, not maintainable, but without more information, I can't do any better. However Regex would be much nicer!

How do I convert String to Number according to locale (opposite of .toLocaleString)?

If I do:
var number = 3500;
alert(number.toLocaleString("hi-IN"));
I will get ३,५०० in Hindi.
But how can I convert it back to 3500.
I want something like:
var str='३,५००';
alert(str.toLocaleNumber("en-US"));
So, that it can give 3500.
Is it possible by javascript or jquery?

I think you are looking for something like:
https://github.com/jquery/globalize
Above link will take you to git project page. This is a js library contributed by Microsoft.
You should give it one try and try to use formt method of that plugin. If you want to study this plugin, here is the link for the same:
http://weblogs.asp.net/scottgu/jquery-globalization-plugin-from-microsoft
I hope this is what you are looking for and will resolve your problem soon. If it doesn't work, let me know.

Recently I've been struggling with the same problem of converting stringified number formatted in any locale back to the number.
I've got inspired by the solution implemented in NG Prime InputNumber component. They use Intl.NumberFormat.prototype.format() (which I recommend) to format the value to locale string, and then create set of RegExp expressions based on simple samples so they can cut off particular expressions from formatted string.
This solution can be simplified with using Intl.Numberformat.prototype.formatToParts(). This method returns information about grouping/decimal/currency and all the other separators used to format your value in particular locale, so you can easily clear them out of previously formatted string. It seems to be the easiest solution, that will cover all cases, but you must know in what locale the value has been previously formatted.
Why Ng Prime didn't go this way? I think its because Intl.Numberformat.prototype.formatToParts() does not support IE11, or perhaps there is something else I didn't notice.
A complete code example using this solution can be found here.

Unfortunately you will have to tackle the localisation manually. Inspired by this answer , I created a function that will manually replace the Hindi numbers:
function parseHindi(str) {
return Number(str.replace(/[०१२३४५६७८९]/g, function (d) {
return d.charCodeAt(0) - 2406;
}).replace(/[०१२३४५६७८९]/g, function (d) {
return d.charCodeAt(0) - 2415;
}));
}
alert(parseHindi("३५००"));
Fiddle here: http://jsfiddle.net/yyxgxav4/

You can try this out
function ConvertDigits(input, source, target) {
var systems = {
arabic: 48, english: 48, tamil: 3046, kannada: 3302, telugu: 3174, hindi: 2406,
malayalam: 3430, oriya: 2918, gurmukhi: 2662, nagari: 2534, gujarati: 2790,
},
output = [], offset = 0, zero = 0, nine = 0, char = 0;
source = source.toLowerCase();
target = target.toLowerCase();
if (!(source in systems && target in systems) || input == null || typeof input == "undefined" || typeof input == "object") {
return input;
}
input = input.toString();
offset = systems[target] - systems[source];
zero = systems[source];
nine = systems[source] + 9;
for (var i = 0 ; i < input.length; i++) {
var char = input.charCodeAt(i);
if (char >= zero && char <= nine) {
output.push(String.fromCharCode(char + offset));
} else {
output.push(input[i]);
}
}
return output.join("");
}
var res = ConvertDigits('१२३४५६७८९', 'hindi', 'english');
I got it from here
If you need a jquery thing then please try this link

Use the Globalize library.
Install it
npm install globalize cldr-data --save
then
var cldr = require("cldr-data");
var Globalize = require("globalize");
Globalize.load(cldr("supplemental/likelySubtags"));
Globalize.load(cldr("supplemental/numberingSystems"));
Globalize.load(cldr("supplemental/currencyData"));
//replace 'hi' with appropriate language tag
Globalize.load(cldr("main/hi/numbers"));
Globalize.load(cldr("main/hi/currencies"));
//You may replace the above locale-specific loads with the following line,
// which will load every type of CLDR language data for every available locale
// and may consume several hundred megs of memory!
//Use with caution.
//Globalize.load(cldr.all());
//Set the locale
//We use the extention u-nu-native to indicate that Devanagari and
// not Latin numerals should be used.
// '-u' means extension
// '-nu' means number
// '-native' means use native script
//Without -u-nu-native this example will not work
//See
// https://en.wikipedia.org/wiki/IETF_language_tag#Extension_U_.28Unicode_Locale.29
// for more details on the U language code extension
var hindiGlobalizer = Globalize('hi-IN-u-nu-native');
var parseHindiNumber = hindiGlobalizer.numberParser();
var formatHindiNumber = hindiGlobalizer.numberFormatter();
var formatRupeeCurrency = hindiGlobalizer.currencyFormatter("INR");
console.log(parseHindiNumber('३,५००')); //3500
console.log(formatHindiNumber(3500)); //३,५००
console.log(formatRupeeCurrency(3500)); //₹३,५००.००
https://github.com/codebling/globalize-example

A common scenario for this problem is to display a float number to the user and then want it back as a numerical value.
In that case, javascript has the number in the first place and looses it when formatting it for display. A simple workaround for the parsing is to store the real float value along with the formatted value:
var number = 3500;
div.innerHTML = number.toLocaleString("hi-IN");
div.dataset.value = number;
Then get it back by parsing the data attribute:
var number = parseFloat(div.dataset.value);
This is a Columbus's egg style answer. It works provided the problem is an egg.

var number = 3500;
var toLocaleString = number.toLocaleString("hi-IN")
var formatted = toLocaleString.replace(',','')
var converted = parseInt(formatted)

d3.format thousand separator on variables?

Hello I'm yet again stuck on d3...
I'd like to know how to use a thousand seperator on a variable all the examples I've managed to find seem to be on static data.
This is what I've tried so far:
d3.csv("OrderValueToday.csv", function(obj) {
var text = 'Today = £';
var totalSales = text + d3.format(",") + obj[0].Today;
svgLabel = d3.select("#label").append("h2")
.text (totalSales);
});
However it just outputs a load a stuff on the webpage this is it:
Today = £function (n){var e=d;if(m&&n%1)return"";var u=0>n||0===n&&0>1/n?(n=-n,"-"):a; if(0>p){var c=Zo.formatPrefix(n,h);n=c.scale(n),e=c.symbol+d}else n*=p;n=g(n,h);var x=n.lastIndexOf("."),M=0>x?n:n.substring(0,x),_=0>x?"":t+n.substring(x+1);!s&&f&&(M=i(M));var b=v.length+M.length+_.length+(y?0:u.length),w=l>b?new Array(b=l-b+1).join(r):"";return y&&(M=i(w+M)),u+=v,n=M+_,("<"===o?u+n+w:">"===o?w+u+n:"^"===o?w.substring(0,b>>=1)+u+n+w.substring(b):u+(y?n:w+n))+e}20000
So all I want is to be able to make the totalSales value have thousand separators so like 20,000 everything else I've tried doesnt do anything. I've read this https://github.com/mbostock/d3/wiki/Formatting but didnt see what I could do for my scenario.
Any help would be greatly appreciated. Cheers

Specifying a d3.format returns a formatting function, which you must then call as a function, passing in the number to be formatted as an argument:
var myNumber = 22400;
d3.format(',')(myNumber); // returns '22,400'
Sometimes you will see a format function stored as a variable like this:
var commaFormat = d3.format(',');
commaFormat(1234567); // returns '1,234,567'
In your case, you could do the following:
var totalSales = text + d3.format(',')(obj[0].Today);

ExtJS 4.1.1: Evaluating a field in a grid

I'm struggling with a ExtJS 4.1.1 grid that has editable cells (CellEditing plugin).
A person should be able to type a mathematic formula into the cell and it should generate the result into the field's value. For example: If a user types (320*10)/4 the return should be 800. Or similar if the user types (320m*10cm)/4 the function should strip the non-mathematical characters from the formula and then calculate it.
I was looking to replace (or match) with a RegExp, but I cannot seem to get it to work. It keeps returning NaN and when I do console.log(e.value); it returns only the originalValue and not the value that I need.
I don't have much code to attach:
onGridValidateEdit : function(editor,e,opts) {
var str = e.value.toString();
console.log(str);
var strCalc = str.match(/0-9+-*\/()/g);
console.log(strCalc);
var numCalc = Number(eval(strCalc));
console.log(numCalc);
return numCalc;
},
Which returns: str=321 strCalc=null numCalc=0 when I type 321*2.
Any help appreciated,
GR.
Update:
Based on input by Paul Schroeder, I created this:
onGridValidateEdit : function(editor,e,opts) {
var str = e.record.get(e.field).toString();
var strCalc = str.replace(/[^0-9+*-/()]/g, "");
var numCalc = Number(eval(strCalc));
console.log(typeof numCalc);
console.log(numCalc);
return numCalc;
},
Which calculates the number, but I am unable to print it back to the grid itself. It shows up as "NaN" even though in console it shows typeof=number and value=800.
Final code:
Here's the final code that worked:
onGridValidateEdit : function(editor,e,opts) {
var fldName = e.field;
var str = e.record.get(fldName).toString();
var strCalc = str.replace(/[^0-9+*-/()]/g, "");
var numCalc = Number(eval(strCalc));
e.record.set(fldName,numCalc);
},

Lets break this code down.
onGridValidateEdit : function(editor,e,opts) {
var str = e.value.toString();
What listener is this code being used in? This is very important for us to know, here's how I set up my listeners in the plugin:
listeners: {
edit: function(editor, e){
var record = e.record;
var str = record.get("your data_index of the value");
}
}
Setting it up this way works for me, So lets move on to:
var strCalc = str.match(/0-9+-*\/()/g);
console.log(strCalc);
at which point strCalc=null, this is also correct. str.match returns null because your regex does not match anything in the string. What I think you want to do instead is this:
var strCalc = str.replace(/[^0-9+*-]/g, "");
console.log(strCalc);
This changes it to replace all characters in the string that aren't your equation operators and numbers. After that I think it should work for whole numbers. I think that you may actually want decimal numbers too, but I can't think of the regex for that off the top of my head (the . needs to be escaped somehow), but it should be simple enough to find in a google search.