Develop Reference

how to truncate output values in Nerdamer

I am using nerdamer.solve to solve roots but the roots are long and not truncated. I wanted to get truncated values upto 4 decimal places. How can I achieve this?
I am using the following code to solve and display output in html:
var r = nerdamer.solve(`1 - ${a} * x^(${p}) + ${b}`, 'x');
document.getElementById("polesAns").innerHTML= r.toString();
The folllowing is output:
[(138655807/135201312)*i+49385501/48155102,(-138655807/135201312)*i+49385501/48155102,(58886197/57419096)*i-49385501/48155102,(-58886197/57419096)*i-49385501/48155102,-560373381/386371730,172668482/119053157,(145619303/100403024)*i-5753750945848186/10000000000000000000000000000000,(-560373381/386371730)*i-5753750945848186/10000000000000000000000000000000]
There is no division performed also.
I tried the solution posted here:
How to use .toFixed() (or any alternative) on Nerdamer.solve solutions?
But how can I do this with my code? I tried the following:
var value = `1 - ${a} * x^(${p}) + ${b}`;
var toFixed = function(value, n) {
var img = Number(nerdamer.imagpart(value).text()).toFixed(n);
var real = Number(nerdamer.realpart(value).text()).toFixed(n);
// Format the number assuming i denotes imaginary in your case
var formatted = '';
if(real !== '0.0000') {
formatted += real;
}
if(img !== '0.0000') {
// Put the plus sign betweent the real and imaginary
if(img.charAt(0) !== '-' && formatted) {
formatted += '+';
}
// Assuming you're using i and not j for instance
formatted += img+'i';
}
return formatted;
};
sol_raw = this.nerdamer.solve(value,'s');
xs = this.nerdamer(sol_raw.toString()).each(function(solution) {
roundedSolutions.push(toFixed(solution, 4));
});
this.setState({
solution: roundedSolution.join(''),
equation:value})
document.getElementById("polesAns").value = solution.toString();
I don't understand the this.setState() part , should i declare sol_raw and xs as var?
Also the substitution of variable is used in the my above root equation from advice here javascript Solving equation with subsitution of variable value
thank you

Replace accented characters with their unaccented equivalent

I have a text field that can not allow accents. I was using this code:
<input type="text" onkeyup="value=value.replace(/[^0-9a-zA-Z' ']/g,'')">
But rather than blocking the characters, I need them to be replaced for example by typing Ç change to C
I found a function and hes working, but when I type a dot appears the letter A
Can you help me?
<script>function retiraAcento(palavra,obj){
com_acento = 'áàãâäéèêëíìîïóòõôöúùûüçÁÀÃÂÄÉÈÊËÍÌÎÏÓÒÕÖÔÚÙÛÜÇ<,>´`-,*/~';
sem_acento = 'aaaaaeeeeiiiiooooouuuucAAAAAEEEEIIIIOOOOOUUUUC ';
nova='';
for(i=0;i<palavra.length;i++) {
if (com_acento.search(palavra.substr(i,1))>=0) {
nova+=sem_acento.substr(com_acento.search(palavra.substr(i,1)),1);
} else {
nova+=palavra.substr(i,1);
}
}
obj.value = nova;}</script><input type="text" onKeyUp="javascript:retiraAcento(this.value, this);">

I didn't dig into it enough to see why the . was being replaced with A, but this version doesn't have that behaviour. It doesn't work exactly the same and it operates on the whole string, but that likely isn't a problem unless it's used in a large textfield, in which case it could be optimised other ways.
const com_acento = 'áàãâäéèêëíìîïóòõôöúùûüçÁÀÃÂÄÉÈÊËÍÌÎÏÓÒÕÖÔÚÙÛÜÇ<,>´`-,~';
const sem_acento = 'aaaaaeeeeiiiiooooouuuucAAAAAEEEEIIIIOOOOOUUUUC ';
function retiraAcento(string) {
return string
.split('')
.map(char => {
const charIdx = com_acento.indexOf(char)
if (charIdx !== -1) {
return sem_acento[charIdx]
}
return char
})
.join('')
}
function replaceCharOnChange(evt) {
event.target.value = retiraAcento(evt.target.value)
}
document.querySelector('input').addEventListener('keyup', replaceCharOnChange)
Apologies it's half rewritten in english! I'd also look into using another data structure than the two same-length strings. The simplest would be an object lookup table eg:
{á: 'a', ç: 'c', ...}
but there's other ways you could go about it too

remove all Decimals and single numbers from array / string

so my script generates a big blob of "Piano Notes" which are similar to...
var songNotes = "...";
the large Piano notes content
and my problem is between the piano notes which i need [also in the fiddle] there are empty ",," and decimal numbers.. so i cant figure out how to remove the empty
,, and decimals as big as
"1.0416666666642413,0.625,0,g3,1498.9583333333358,,0,c3,1.0416666666642413,0.625,0,c3"
and i want them removed except the the needed words which are
var theRightOnes = "s2,as2,cs3,ds3,fs3,gs3,as3,gs3,cs4,ds4,fs4,cs3,as4,gs4,ds5,a2,cs4,b2,c3,a3,ds4,b3,c4,as3,gs2,e3,c3,c4,cs3,ds3,a4,fs3,gs3,as3,g3,f3,b4,c5,a3,d4,as2,e4,g4,d3,b3,b2,f4,a2,d4,e4,cs5,gs1,e2,c2,c3,cs2,ds2,a3,fs2,gs2,as2,g2,f2,b3,c4,a2,d3,as1,e3,g3,d2,b2,b1,f3,a1,d5,e5";
so can anyone give me a clue on how this can be accomplished?
if anyone needs more info then i am ready oblige to do so..
Regards - Adarsh Hegde

var notesArr = songNotes.split(",");
var len = notesArr.length;
while(len--) {
if(!notesArr[len] || !isNaN(parseInt(notesArr[len], 10))) {
notesArr.splice(len, 1);
}
}
songNotes = notesArr.join(",");

I think you want to remove all the numbers from notes.
You can say like bellow
var notes = songNotes.split(",").filter(function(note){
return isNaN(note);
});
console.log(notes);

You can use Array.filter (see MDN) to weed out unwanted values:
var wantedNotes = songNotes.split(',')
.filter(function (v) {
return isNaN(+v) && v.trim().length
});
jsFiddle

just use regular expression,like this:
var a = "1.0416666666642413,0.625,0,g3,1498.9583333333358,,0,c3,1.0416666666642413,0.625,0,c3";
console.log(a.replace(/\b(\d+(\.\d+)?),+/g,""));

Javascript (or jQuery) string replacement

So, I have strings pulled from a JSON array like this:
Hg22+
CO32-
Al3Cl23+
These numbers need to be superscript or subscript, with rules. It's only numbers 0-9, and if that number has a plus or minus after it, it needs to be superscript, meaning I need to change the string to <sup>3+</sup>. All other numbers, if they haven't been superscripted, need to be subscripted. Here are a few examples of what I need:
C12H22O11 (s, sucrose) = <sub>1</sub><sub>2</sub>H<sub>2</sub><sub>2</sub>O<sub>1</sub><sub>1</sub> (s, sucrose)
Al3Cl23+ = Al<sub>3</sub>Cl<sub>2</sub><sup>3+</sup>
Hg22+ = Hg<sub>2</sub><sup>2+</sup>
I can do it, but very sloppily. I am really open to a good way to change string like above. If anyone can help out I'd be really appreciative!
Thanks!

Easy.
var result = input.replace(/\d([+-]?)/g,function(match,plus) {
var s = plus ? "sup" : "sub";
return "<"+s+">"+match+"</"+s+">";
});
Done.

Slightly modified from #Niet the Dark Absol's answer
var tests = ['Hg22+', 'CO32-', 'Al3Cl23+','C12H22O11 (s, sucrose)'];
function chemize(input) {
return input.replace(/\d([\+\-]?)/g,function(match,plus) {
var s = plus ? "sup" : "sub";
return "<"+s+">"+match+"</"+s+">";
});
}
for(var z in tests) {
var test = tests[z];
console.log('"' + test + '" --> ' + chemize(test) );
}
Output:
"Hg22+" --> Hg<sub>2</sub><sup>2+</sup>
"CO32-" --> CO<sub>3</sub><sup>2-</sup>
"Al3Cl23+" --> Al<sub>3</sub>Cl<sub>2</sub><sup>3+</sup>
"C12H22O11 (s, sucrose)" --> C<sub>1</sub><sub>2</sub>H<sub>2</sub><sub>2</sub>O<sub>1</sub><sub>1</sub> (s, sucrose)

How to achieve String Manipulation in JavaScript

The problem statement is like this: I have a contract. On renewal on every month the contract name should append with renewal identifier. For example at beginning the name is myContract then on first renewal name should be myContract-R1, next renewal name should be myContract-R2 and so on.. On each renewal, the name should automatically change. So in Jquery how can I do this?

This is a JavaScript question, not a jQuery question. jQuery adds little to JavaScript's built-in string manipulation.
It sounds like you want to take a string in the form "myContract" or "myContract-Rx" and have a function that appends "-R1" (if there's no "-Rx" already) or increments the number that's there.
There's no shortcut for that, you have to do it. Here's a sketch that works, I expect it could be optimized:
function incrementContract(name) {
var match = /^(.*)-R([0-9]+)$/.exec(name);
if (match) {
// Increment previous revision number
name = match[1] + "-R" + (parseInt(match[2], 10) + 1);
}
else {
// No previous revision number
name += "-R1";
}
return name;
}
Live copy

You can use a regular expression for this:
s = s.replace(/(-R\d+)?$/, function(m) {
return '-R' + (m.length === 0 ? 1 : parseInt(m.substr(2), 10) + 1);
});
The pattern (-R\d+)?$ will match the revision number (-R\d+) if there is one (?), and the end of the string ($).
The replacement will return -R1 if there was no revision number before, otherwise it will parse the revision number and increment it.

how you get renewal number? Calculating from date, or getting from database?
var renewal = 1,
name = 'myContract',
newname = name+'R'+renewal;
or maybe like
$(function(){
function renew(contract){
var num_re = /\d+/,
num = contract.match(num_re);
if (num==null) {
return contract+'-R1';
} else {
return contract.replace(num_re,++num[0]);
}
}
var str = 'myContract';
new_contract = renew(str); // myContract-1
new_contract = renew(new_contract); // myContract-2
new_contract = renew(new_contract); // myContract-3
});
Here jQuery can't help you. It's pure JavaScript working with strings
P.S. I have here simple reg exp, that's not concrete for your example (but it works). Better use reg-exp from example of T.J. Crowder