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Not sure why this JavaScript function is not working

I am writing JavaScript / HTML for a project for one of my classes. I'm not sure why the JavaScript function won't execute. The first return ("result") works no problem but for some reason my program wont work for ("result2"). I pasted the function down below:
function multiplyBy(){
var x = document.getElementById("text").value;
var y = document.getElementById("text2").value;
var z = x * y;
var a = 52 * z;
var b = paraseFloat(a);
if (b > 20000) {
output = "The Salary is too little."
}
if else (b < 20000; b > 25000) {
output = "The Salary is almost enough. Let's negotiate."
}
else {
output = "This is a great salary for me."
}
return document.getElementById("result").innerHTML = "The Salary is: " + b;
return document.getElementById("result2").innerHTML = output
}

You have few issues in the code
paraseFloat is a miss type it should be parseFloat
if else (b < 20000; b > 25000) {
if else should be else if
if you want to have a range in your check you need to add logical operators like && ||
and the you need to review the logic for checking the salary i am not sure but i have changed something that "has" some sense
you can check in here
function multiplyBy() {
var x = document.getElementById("text").value;
var y = document.getElementById("text2").value;
var z = x * y;
var a = 52 * z;
var b = parseFloat(a);
if (b < 20000) {
output = "The Salary is too little.";
} else if (b >= 20000 && b < 25000) {
output = "The Salary is almost enough. Let's negotiate.";
} else {
output = "This is a great salary for me.";
}
document.getElementById("result").innerHTML = "The Salary is: " + b;
document.getElementById("result2").innerHTML = output;
}
multiplyBy();
<input type='text' name='text' id='text' value=10 />
<input type='text' name='text2' id='text2' value=10 />
<div id='result'></div>
<div id='result2'></div>

I have found couple of issues in your code but you were almost there. Let me summarize in few steps where it was wrong:
In your code if else was presented. Using else if works other way around, read further here.
Logical AND operator for defining between values for salary works differently, here you can find details. b < 20000; b > 25000 is just wrongly defined, I have corrected to have b >= 20000 && b < 25000. Solution uses && and changed a bit the condition.
In parsing to float case there was a typo in your function call, should have parseFloat instead of paraseFloat. Read further here.
Just changed from b < 20000 to b > 20000 which makes more sense in terms of text result.
And lastly, in your function there are 2 return statements, even if there is no need at all in that code. The function manipulates the DOM then it will automatically return undefined. Please find here the documentation for more details which states:
A function without a return statement will return a default value. ... For all other functions, the default return value is undefined.
And finally here is a working solution:
function multiplyBy() {
const x = document.getElementById("text").value;
const y = document.getElementById("text2").value;
const z = x * y;
const a = 52 * z;
const b = parseFloat(a);
if (b < 20000) {
output = "The Salary is too little.";
} else if (b >= 20000 && b < 25000) {
output = "The Salary is almost enough. Let's negotiate.";
} else {
output = "This is a great salary for me.";
}
document.getElementById("result").innerHTML = "The Salary is: " + b;
document.getElementById("result2").innerHTML = output;
}
<input id="text" />
<input id="text2" />
<div id="result"></div>
<div id="result2"></div>
<button onclick="multiplyBy()">Calculate</button>
Additionally it is worth to read further about when to use const, let and var.
Hope this helps!

Troubleshooting the use of if/else inside a event function

I am having trouble using an if else to achieve a simple two-way celsius/fahrenheit conversion using basic HTML input fields and some background Javascript.
Basically, I want to be able to enter a value in C or F into one of the two inputs and then have the conversion appear in the other input. The Celsius to Fahrenheit conversion works OK, but nothing happens when entering numbers into the Fahrenheit input. My code is below
var celsius = document.getElementById("Celsius");
var fahrenheit = document.getElementById("Fahrenheit");
celsius.addEventListener('input', conversion);
fahrenheit.addEventListener('input', conversion);
function conversion() {
var celsiusvalue = document.getElementById("Celsius").value;
var fahrenheitvalue = document.getElementById("Fahrenheit").value;
const intcelsius = parseInt(celsiusvalue, 10);
const intfahrenheit = parseInt(fahrenheitvalue, 10);
if (this.id == "Celsius") {
fahrenheit.value = ((intcelsius * 9)/5) + 32;
}
else {
celsius.value == (((intfahrenheit - 32) * 5) / 9);
}
}
<section>
<input id="Celsius" placeholder="Celsius"/><br/><br/>
<input id="Fahrenheit" placeholder="Fahrenheit"/>
</section>
Can anyone help me out? Should I not be using if/else here and just use two different functions?

celsius.value == (((intfahrenheit - 32) * 5) / 9);
should be:
celsius.value = (((intfahrenheit - 32) * 5) / 9);

which are alternative of tofixed() in javascript [duplicate]

Suppose I have a value of 15.7784514, I want to display it 15.77 with no rounding.
var num = parseFloat(15.7784514);
document.write(num.toFixed(1)+"<br />");
document.write(num.toFixed(2)+"<br />");
document.write(num.toFixed(3)+"<br />");
document.write(num.toFixed(10));
Results in -
15.8
15.78
15.778
15.7784514000
How do I display 15.77?

Convert the number into a string, match the number up to the second decimal place:
function calc(theform) {
var num = theform.original.value, rounded = theform.rounded
var with2Decimals = num.toString().match(/^-?\d+(?:\.\d{0,2})?/)[0]
rounded.value = with2Decimals
}
<form onsubmit="return calc(this)">
Original number: <input name="original" type="text" onkeyup="calc(form)" onchange="calc(form)" />
<br />"Rounded" number: <input name="rounded" type="text" placeholder="readonly" readonly>
</form>
The toFixed method fails in some cases unlike toString, so be very careful with it.

Update 5 Nov 2016
New answer, always accurate
function toFixed(num, fixed) {
var re = new RegExp('^-?\\d+(?:\.\\d{0,' + (fixed || -1) + '})?');
return num.toString().match(re)[0];
}
As floating point math in javascript will always have edge cases, the previous solution will be accurate most of the time which is not good enough.
There are some solutions to this like num.toPrecision, BigDecimal.js, and accounting.js.
Yet, I believe that merely parsing the string will be the simplest and always accurate.
Basing the update on the well written regex from the accepted answer by #Gumbo, this new toFixed function will always work as expected.
Old answer, not always accurate.
Roll your own toFixed function:
function toFixed(num, fixed) {
fixed = fixed || 0;
fixed = Math.pow(10, fixed);
return Math.floor(num * fixed) / fixed;
}

Another single-line solution :
number = Math.trunc(number*100)/100
I used 100 because you want to truncate to the second digit, but a more flexible solution would be :
number = Math.trunc(number*Math.pow(10, digits))/Math.pow(10, digits)
where digits is the amount of decimal digits to keep.
See Math.trunc specs for details and browser compatibility.

I opted to write this instead to manually remove the remainder with strings so I don't have to deal with the math issues that come with numbers:
num = num.toString(); //If it's not already a String
num = num.slice(0, (num.indexOf("."))+3); //With 3 exposing the hundredths place
Number(num); //If you need it back as a Number
This will give you "15.77" with num = 15.7784514;

Update (Jan 2021)
Depending on its range, a number in javascript may be shown in scientific notation. For example, if you type 0.0000001 in the console, you may see it as 1e-7, whereas 0.000001 appears unchanged (0.000001).
If your application works on a range of numbers for which scientific notation is not involved, you can just ignore this update and use the original answer below.
This update is about adding a function that checks if the number is in scientific format and, if so, converts it into decimal format. Here I'm proposing this one, but you can use any other function that achieves the same goal, according to your application's needs:
function toFixed(x) {
if (Math.abs(x) < 1.0) {
let e = parseInt(x.toString().split('e-')[1]);
if (e) {
x *= Math.pow(10,e-1);
x = '0.' + (new Array(e)).join('0') + x.toString().substring(2);
}
} else {
let e = parseInt(x.toString().split('+')[1]);
if (e > 20) {
e -= 20;
x /= Math.pow(10,e);
x += (new Array(e+1)).join('0');
}
}
return x;
}
Now just apply that function to the parameter (that's the only change with respect to the original answer):
function toFixedTrunc(x, n) {
x = toFixed(x)
// From here on the code is the same than the original answer
const v = (typeof x === 'string' ? x : x.toString()).split('.');
if (n <= 0) return v[0];
let f = v[1] || '';
if (f.length > n) return `${v[0]}.${f.substr(0,n)}`;
while (f.length < n) f += '0';
return `${v[0]}.${f}`
}
This updated version addresses also a case mentioned in a comment:
toFixedTrunc(0.000000199, 2) => "0.00"
Again, choose what fits your application needs at best.
Original answer (October 2017)
General solution to truncate (no rounding) a number to the n-th decimal digit and convert it to a string with exactly n decimal digits, for any n≥0.
function toFixedTrunc(x, n) {
const v = (typeof x === 'string' ? x : x.toString()).split('.');
if (n <= 0) return v[0];
let f = v[1] || '';
if (f.length > n) return `${v[0]}.${f.substr(0,n)}`;
while (f.length < n) f += '0';
return `${v[0]}.${f}`
}
where x can be either a number (which gets converted into a string) or a string.
Here are some tests for n=2 (including the one requested by OP):
0 => 0.00
0.01 => 0.01
0.5839 => 0.58
0.999 => 0.99
1.01 => 1.01
2 => 2.00
2.551 => 2.55
2.99999 => 2.99
4.27 => 4.27
15.7784514 => 15.77
123.5999 => 123.59
And for some other values of n:
15.001097 => 15.0010 (n=4)
0.000003298 => 0.0000032 (n=7)
0.000003298257899 => 0.000003298257 (n=12)

parseInt is faster then Math.floor
function floorFigure(figure, decimals){
if (!decimals) decimals = 2;
var d = Math.pow(10,decimals);
return (parseInt(figure*d)/d).toFixed(decimals);
};
floorFigure(123.5999) => "123.59"
floorFigure(123.5999, 3) => "123.599"

num = 19.66752
f = num.toFixed(3).slice(0,-1)
alert(f)
This will return 19.66

Simple do this
number = parseInt(number * 100)/100;

Just truncate the digits:
function truncDigits(inputNumber, digits) {
const fact = 10 ** digits;
return Math.floor(inputNumber * fact) / fact;
}

This is not a safe alternative, as many others commented examples with numbers that turn into exponential notation, that scenery is not covered by this function
// typescript
// function formatLimitDecimals(value: number, decimals: number): number {
function formatLimitDecimals(value, decimals) {
const stringValue = value.toString();
if(stringValue.includes('e')) {
// TODO: remove exponential notation
throw 'invald number';
} else {
const [integerPart, decimalPart] = stringValue.split('.');
if(decimalPart) {
return +[integerPart, decimalPart.slice(0, decimals)].join('.')
} else {
return integerPart;
}
}
}
console.log(formatLimitDecimals(4.156, 2)); // 4.15
console.log(formatLimitDecimals(4.156, 8)); // 4.156
console.log(formatLimitDecimals(4.156, 0)); // 4
console.log(formatLimitDecimals(0, 4)); // 0
// not covered
console.log(formatLimitDecimals(0.000000199, 2)); // 0.00

These solutions do work, but to me seem unnecessarily complicated. I personally like to use the modulus operator to obtain the remainder of a division operation, and remove that. Assuming that num = 15.7784514:
num-=num%.01;
This is equivalent to saying num = num - (num % .01).

I fixed using following simple way-
var num = 15.7784514;
Math.floor(num*100)/100;
Results will be 15.77

My version for positive numbers:
function toFixed_norounding(n,p)
{
var result = n.toFixed(p);
return result <= n ? result: (result - Math.pow(0.1,p)).toFixed(p);
}
Fast, pretty, obvious. (version for positive numbers)

The answers here didn't help me, it kept rounding up or giving me the wrong decimal.
my solution converts your decimal to a string, extracts the characters and then returns the whole thing as a number.
function Dec2(num) {
num = String(num);
if(num.indexOf('.') !== -1) {
var numarr = num.split(".");
if (numarr.length == 1) {
return Number(num);
}
else {
return Number(numarr[0]+"."+numarr[1].charAt(0)+numarr[1].charAt(1));
}
}
else {
return Number(num);
}
}
Dec2(99); // 99
Dec2(99.9999999); // 99.99
Dec2(99.35154); // 99.35
Dec2(99.8); // 99.8
Dec2(10265.985475); // 10265.98

The following code works very good for me:
num.toString().match(/.\*\\..{0,2}|.\*/)[0];

This worked well for me. I hope it will fix your issues too.
function toFixedNumber(number) {
const spitedValues = String(number.toLocaleString()).split('.');
let decimalValue = spitedValues.length > 1 ? spitedValues[1] : '';
decimalValue = decimalValue.concat('00').substr(0,2);
return '$'+spitedValues[0] + '.' + decimalValue;
}
// 5.56789 ----> $5.56
// 0.342 ----> $0.34
// -10.3484534 ----> $-10.34
// 600 ----> $600.00
function convertNumber(){
var result = toFixedNumber(document.getElementById("valueText").value);
document.getElementById("resultText").value = result;
}
function toFixedNumber(number) {
const spitedValues = String(number.toLocaleString()).split('.');
let decimalValue = spitedValues.length > 1 ? spitedValues[1] : '';
decimalValue = decimalValue.concat('00').substr(0,2);
return '$'+spitedValues[0] + '.' + decimalValue;
}
<div>
<input type="text" id="valueText" placeholder="Input value here..">
<br>
<button onclick="convertNumber()" >Convert</button>
<br><hr>
<input type="text" id="resultText" placeholder="result" readonly="true">
</div>

An Easy way to do it is the next but is necessary ensure that the amount parameter is given as a string.
function truncate(amountAsString, decimals = 2){
var dotIndex = amountAsString.indexOf('.');
var toTruncate = dotIndex !== -1 && ( amountAsString.length > dotIndex + decimals + 1);
var approach = Math.pow(10, decimals);
var amountToTruncate = toTruncate ? amountAsString.slice(0, dotIndex + decimals +1) : amountAsString;
return toTruncate
? Math.floor(parseFloat(amountToTruncate) * approach ) / approach
: parseFloat(amountAsString);
}
console.log(truncate("7.99999")); //OUTPUT ==> 7.99
console.log(truncate("7.99999", 3)); //OUTPUT ==> 7.999
console.log(truncate("12.799999999999999")); //OUTPUT ==> 7.99

Here you are. An answer that shows yet another way to solve the problem:
// For the sake of simplicity, here is a complete function:
function truncate(numToBeTruncated, numOfDecimals) {
var theNumber = numToBeTruncated.toString();
var pointIndex = theNumber.indexOf('.');
return +(theNumber.slice(0, pointIndex > -1 ? ++numOfDecimals + pointIndex : undefined));
}
Note the use of + before the final expression. That is to convert our truncated, sliced string back to number type.
Hope it helps!

truncate without zeroes
function toTrunc(value,n){
return Math.floor(value*Math.pow(10,n))/(Math.pow(10,n));
}
or
function toTrunc(value,n){
x=(value.toString()+".0").split(".");
return parseFloat(x[0]+"."+x[1].substr(0,n));
}
test:
toTrunc(17.4532,2) //17.45
toTrunc(177.4532,1) //177.4
toTrunc(1.4532,1) //1.4
toTrunc(.4,2) //0.4
truncate with zeroes
function toTruncFixed(value,n){
return toTrunc(value,n).toFixed(n);
}
test:
toTrunc(17.4532,2) //17.45
toTrunc(177.4532,1) //177.4
toTrunc(1.4532,1) //1.4
toTrunc(.4,2) //0.40

If you exactly wanted to truncate to 2 digits of precision, you can go with a simple logic:
function myFunction(number) {
var roundedNumber = number.toFixed(2);
if (roundedNumber > number)
{
roundedNumber = roundedNumber - 0.01;
}
return roundedNumber;
}

I used (num-0.05).toFixed(1) to get the second decimal floored.

It's more reliable to get two floating points without rounding.
Reference Answer
var number = 10.5859;
var fixed2FloatPoints = parseInt(number * 100) / 100;
console.log(fixed2FloatPoints);
Thank You !

My solution in typescript (can easily be ported to JS):
/**
* Returns the price with correct precision as a string
*
* #param price The price in decimal to be formatted.
* #param decimalPlaces The number of decimal places to use
* #return string The price in Decimal formatting.
*/
type toDecimal = (price: number, decimalPlaces?: number) => string;
const toDecimalOdds: toDecimal = (
price: number,
decimalPlaces: number = 2,
): string => {
const priceString: string = price.toString();
const pointIndex: number = priceString.indexOf('.');
// Return the integer part if decimalPlaces is 0
if (decimalPlaces === 0) {
return priceString.substr(0, pointIndex);
}
// Return value with 0s appended after decimal if the price is an integer
if (pointIndex === -1) {
const padZeroString: string = '0'.repeat(decimalPlaces);
return `${priceString}.${padZeroString}`;
}
// If numbers after decimal are less than decimalPlaces, append with 0s
const padZeroLen: number = priceString.length - pointIndex - 1;
if (padZeroLen > 0 && padZeroLen < decimalPlaces) {
const padZeroString: string = '0'.repeat(padZeroLen);
return `${priceString}${padZeroString}`;
}
return priceString.substr(0, pointIndex + decimalPlaces + 1);
};
Test cases:
expect(filters.toDecimalOdds(3.14159)).toBe('3.14');
expect(filters.toDecimalOdds(3.14159, 2)).toBe('3.14');
expect(filters.toDecimalOdds(3.14159, 0)).toBe('3');
expect(filters.toDecimalOdds(3.14159, 10)).toBe('3.1415900000');
expect(filters.toDecimalOdds(8.2)).toBe('8.20');
Any improvements?

Another solution, that truncates and round:
function round (number, decimals, truncate) {
if (truncate) {
number = number.toFixed(decimals + 1);
return parseFloat(number.slice(0, -1));
}
var n = Math.pow(10.0, decimals);
return Math.round(number * n) / n;
};

function limitDecimalsWithoutRounding(val, decimals){
let parts = val.toString().split(".");
return parseFloat(parts[0] + "." + parts[1].substring(0, decimals));
}
var num = parseFloat(15.7784514);
var new_num = limitDecimalsWithoutRounding(num, 2);

Roll your own toFixed function: for positive values Math.floor works fine.
function toFixed(num, fixed) {
fixed = fixed || 0;
fixed = Math.pow(10, fixed);
return Math.floor(num * fixed) / fixed;
}
For negative values Math.floor is round of the values. So you can use Math.ceil instead.
Example,
Math.ceil(-15.778665 * 10000) / 10000 = -15.7786
Math.floor(-15.778665 * 10000) / 10000 = -15.7787 // wrong.

Gumbo's second solution, with the regular expression, does work but is slow because of the regular expression. Gumbo's first solution fails in certain situations due to imprecision in floating points numbers. See the JSFiddle for a demonstration and a benchmark. The second solution takes about 1636 nanoseconds per call on my current system, Intel Core i5-2500 CPU at 3.30 GHz.
The solution I've written involves adding a small compensation to take care of floating point imprecision. It is basically instantaneous, i.e. on the order of nanoseconds. I clocked 2 nanoseconds per call but the JavaScript timers are not very precise or granular. Here is the JS Fiddle and the code.
function toFixedWithoutRounding (value, precision)
{
var factorError = Math.pow(10, 14);
var factorTruncate = Math.pow(10, 14 - precision);
var factorDecimal = Math.pow(10, precision);
return Math.floor(Math.floor(value * factorError + 1) / factorTruncate) / factorDecimal;
}
var values = [1.1299999999, 1.13, 1.139999999, 1.14, 1.14000000001, 1.13 * 100];
for (var i = 0; i < values.length; i++)
{
var value = values[i];
console.log(value + " --> " + toFixedWithoutRounding(value, 2));
}
for (var i = 0; i < values.length; i++)
{
var value = values[i];
console.log(value + " --> " + toFixedWithoutRounding(value, 4));
}
console.log("type of result is " + typeof toFixedWithoutRounding(1.13 * 100 / 100, 2));
// Benchmark
var value = 1.13 * 100;
var startTime = new Date();
var numRun = 1000000;
var nanosecondsPerMilliseconds = 1000000;
for (var run = 0; run < numRun; run++)
toFixedWithoutRounding(value, 2);
var endTime = new Date();
var timeDiffNs = nanosecondsPerMilliseconds * (endTime - startTime);
var timePerCallNs = timeDiffNs / numRun;
console.log("Time per call (nanoseconds): " + timePerCallNs);

Building on David D's answer:
function NumberFormat(num,n) {
var num = (arguments[0] != null) ? arguments[0] : 0;
var n = (arguments[1] != null) ? arguments[1] : 2;
if(num > 0){
num = String(num);
if(num.indexOf('.') !== -1) {
var numarr = num.split(".");
if (numarr.length > 1) {
if(n > 0){
var temp = numarr[0] + ".";
for(var i = 0; i < n; i++){
if(i < numarr[1].length){
temp += numarr[1].charAt(i);
}
}
num = Number(temp);
}
}
}
}
return Number(num);
}
console.log('NumberFormat(123.85,2)',NumberFormat(123.85,2));
console.log('NumberFormat(123.851,2)',NumberFormat(123.851,2));
console.log('NumberFormat(0.85,2)',NumberFormat(0.85,2));
console.log('NumberFormat(0.851,2)',NumberFormat(0.851,2));
console.log('NumberFormat(0.85156,2)',NumberFormat(0.85156,2));
console.log('NumberFormat(0.85156,4)',NumberFormat(0.85156,4));
console.log('NumberFormat(0.85156,8)',NumberFormat(0.85156,8));
console.log('NumberFormat(".85156",2)',NumberFormat(".85156",2));
console.log('NumberFormat("0.85156",2)',NumberFormat("0.85156",2));
console.log('NumberFormat("1005.85156",2)',NumberFormat("1005.85156",2));
console.log('NumberFormat("0",2)',NumberFormat("0",2));
console.log('NumberFormat("",2)',NumberFormat("",2));
console.log('NumberFormat(85156,8)',NumberFormat(85156,8));
console.log('NumberFormat("85156",2)',NumberFormat("85156",2));
console.log('NumberFormat("85156.",2)',NumberFormat("85156.",2));
// NumberFormat(123.85,2) 123.85
// NumberFormat(123.851,2) 123.85
// NumberFormat(0.85,2) 0.85
// NumberFormat(0.851,2) 0.85
// NumberFormat(0.85156,2) 0.85
// NumberFormat(0.85156,4) 0.8515
// NumberFormat(0.85156,8) 0.85156
// NumberFormat(".85156",2) 0.85
// NumberFormat("0.85156",2) 0.85
// NumberFormat("1005.85156",2) 1005.85
// NumberFormat("0",2) 0
// NumberFormat("",2) 0
// NumberFormat(85156,8) 85156
// NumberFormat("85156",2) 85156
// NumberFormat("85156.",2) 85156

Already there are some suitable answer with regular expression and arithmetic calculation, you can also try this
function myFunction() {
var str = 12.234556;
str = str.toString().split('.');
var res = str[1].slice(0, 2);
document.getElementById("demo").innerHTML = str[0]+'.'+res;
}
// output: 12.23

Here is what is did it with string
export function withoutRange(number) {
const str = String(number);
const dotPosition = str.indexOf('.');
if (dotPosition > 0) {
const length = str.substring().length;
const end = length > 3 ? 3 : length;
return str.substring(0, dotPosition + end);
}
return str;
}

How do I replace every dash (-) with a random number in javascript?

I have have some codes like ABCDE-----ABCD----ABC--, where each (-) needs to be a random number.
I have no problem using the replace function to change a single dash to a random number, but I have no clue how to make each dash a random number. Note: each number doesn't need to be unique.
Here is where I am now, but I need the numbers to not all be the same. http://jsfiddle.net/oqrstsdm/
var minNumber = 1;
var maxNumber = 9;
randomNumberFromRange(minNumber, maxNumber);
function randomNumberFromRange(min, max) {
var number = (Math.floor(Math.random() * (max - min + 1) + min));
var str = "ABCDE-----FGABC--";
var res = new RegExp("-", "g");
var code = str.replace(res, number);
document.getElementById("ccode").innerHTML = "Code: " + code;
}

You could use a function as second argument in String.prototype.replace().
var str = "ABCDE-----FGABC--";
var code = str.replace(/-/g, function() {
return Math.floor(Math.random() * (max - min + 1)) + min;
});

Do it in a while loop. Also you don't actually need a regular expression since you're just looking for a string. If you did want a regexp change str.indexOf("-") !== -1 by str.match(regexp) !== null. You also wont need the g flag with this approach.
var str = "ABCDE-----FGABC--";
var number;
while (str.indexOf("-") !== -1) {
number = Math.floor(Math.random() * 10);
str = str.replace("-", number);
}
return str;
Output:
ABCDE92136FGABC38

As an alternative to the replace method, you can use the String split method to tokenize the code, and then apply an Array reduce method to re-join the values with the appropriate numbers substituted in.
function randomNumberFromRange(min, max) {
var str = "ABCDE-----FGABC--";
return str.split("-").reduce(function(prev, val) {
return prev + rand(min, max) + val;
});
}
function rand(min, max) {
return Math.floor(Math.random() * (max - min + 1) + min);
}
// Demo code
document.getElementById("random").onclick = function() {
document.getElementById("code").innerHTML = randomNumberFromRange(1, 9);
};
<div id="code"></div>
<div>
<button id="random">Get Code</button>
</div>

javascript splitting a var that is numbers and letters

I'd prefer to not use regex, but if needed, so be it.
I have some code and I want to take a user's input and check to make sure that it is an isbn 10. In other words it must be a 10 digit number or a 9 digit number with an x at the end (the x represents the number 10). For my purposes, I'd like to turn the users input into an array of each digit. If there is an x I'd like to change that into a 10. I am having trouble doing this! I have seen other questions that are somewhat similar and they all use regex. Like I said, I'd prefer to not use regex, but if need be...
<h1>Problem #3:</h1>
<form name= "form">
<input id= "input" name= "isbn" type="number" placeholder="Enter your ISBN-10" min="0" />
<input id= "button" type="button" name="Validate" value="Validate" />
</form>
<div id="validISBN">
Valid ISBN
</div>
<div id="invalidISBN">
Invalid ISBN
</div>
<script src="js/jquery-2.0.3.min.js"></script>
<script>
$( document ).ready(function() {
alert("Welcome to ISBN Validator!");
//Add the event listener for the validate button here
//Look at toggling the CSS display property based on the result
$("#button").click(function(){
checker(document.form.isbn.value);
});
});
var checker = function(isbn){
isbn = isbn.toString().split('');
if (isbn[9] == 'x'|| isbn[9] == 'X') {
isbn[9] = 10;
}
if (isbn.length !== 10) {
alert("invalid ISBN!" + isbn.length);
}
else{
var sum = 0;
for (var x=10; x>0; x--){
sum += x*isbn[10-x];
}
alert("FINAL!!" + sum%11);
}
}
Input: 0375726721
Output: FINAL!!0
:Works
Input:067978330X
Expected Output: FINAL!!0
Actual Output: Invalid ISBN!0
:Does not work!

var isbn = '074759582x';
if (!/^\d{9}(\d|x)$/i.test(isbn)) // validation with regexp
alert('Invalid ISBN');
else {
var arr = isbn.split('');
arr[9] = arr[9].toLowerCase() == 'x' ? 10 : arr[9]; // replacement of x by 10
// below is your summation, just performed in another way.
var total = arr.map(function(el, index, arr) {
return (index + 1) * arr[10 - index - 1];
}).reduce(function(a, b) {return a + b;});
alert(total % 11);
}
Done

var isbn = '074759582x';
Split the string into characters using split. Apply map to grab the x and convert it to 10 if necessary. Then map each character to a number
array = isbn
.split('')
.map(function(char, i) {
return i === 9 && char.toLowerCase() === 'x' ? 10 : char;
})
.map(Number)
;
The ISBN is valid if it's of length 10, and there are no NaNs in it.
valid = array.length === 10 && !array.some(isNaN);
Checksum uses reduce, as in another answer:
sum = array.reduce(function(result, v, i) {
return result + (10-i) * v;
}, 0) % 11;

Problem #3:
<form name= "form">
<input id= "input" name= "isbn" type="number" placeholder="Enter your ISBN-10" min="0" />
<input id= "button" type="button" name="Validate" value="Validate" onclick = "checker()" />
</form>
<div id="validISBN">
Valid ISBN
</div>
<div id="invalidISBN">
Invalid ISBN
</div>
<script>
function checker () {
isbn = document.form.isbn.value;
isbn = isbn.toString().split('');
if (isbn[9] == 'x' || isbn[9] == 'X') {
isbn[9] = 10;
}
if (isbn.length !== 10) {
alert("invalid ISBN!" + isbn.length);
}
else {
var sum = 0;
for (var x = 10; x > 0; x--) {
sum += x * isbn[10 - x];
}
alert("FINAL!!" + sum % 11);
}
}
</script>