Develop Reference

Check if string exists in another string (not exactly equal)

I have this 2 strings:
var test = 'BN123';
var behaviour = 'BN***,TA****';
I need to check if behaviour contains a string with the same format as test.
On the behaviour, the BN and TA as to be equal, and the * means it can be any char. (behaviour comes from an API, so I never know what it has, this is just a test.)
In this case it should return true. Right now I'm only comparing is case behaviour as a single string, but I need to modify that:
isValidInput(behaviour, test) {
if (behaviour.length != test.length) {
return false;
}
for (var i = 0; i < behaviour.length; i++) {
if (behaviour.charAt(i) == '*') {
continue;
}
if (behaviour.charAt(i) != test.charAt(i)) {
return false;
}
}
return true;
}

You can use .some() of Array.prototype.
like below
function isValidInput(behaviour, string1) {
if (behaviour.length != string1.length) {
return false;
}
for (var i = 0; i < behaviour.length; i++) {
if (behaviour.charAt(i) == '*') {
continue;
}
if (behaviour.charAt(i) != string1.charAt(i)) {
return false;
}
}
return true;
}
var test = 'BN123';
var behaviour = 'BN***,TA****';
console.log(behaviour.split(',').some(x => isValidInput(x,test)));
console.log(behaviour.split(',').some(x => isValidInput(x,"test")));

The only issue I see with your implementation is that you're not allowing for the fact behaviour contains possible strings separated with a comma (or at least, that's how it looks to me). So you need to check each of them:
// Check one behaviour string from the list
function isOneValidInput(behaviour, string) {
if (behaviour.length != string.length) {
return false;
}
for (var i = 0; i < behaviour.length; i++) {
// Note we can easily combine those conditions, and use []
// with strings
if (behaviour[i] != '*' && behaviour[i] != string[i]) {
return false;
}
}
return true;
}
// Check all behaviour strings in a comma-separated one
function isValidInput(behaviours, string) {
return behaviours.split(",").some(function(behaviour) {
return isOneValidInput(behaviour, string);
});
}
var string = 'BN123';
var behaviour = 'BN***,TA****';
console.log(isValidInput(behaviour, string));
(I stuck to ES5 there because you seemed to be doing so.)

Is this what you want?
var test = 'BN123';
var behaviour = 'BN***,TA****';
var behaviours = behaviour.split(',');
var result = behaviours.map(b => {
if (b.length != test.length)
return false;
var pattern = b.split('*')[0];
return pattern === test.substring(0,pattern.length);
}).find(r => r === true) > -1;
console.log(result)

You can use the new .includes() method to see if a string is contained within another. Note that this is case sensitive. I have included two dodgied up behaviours to check the string against.
var string = 'BN123';
var behaviour1 = 'BN123,TA1234';
var behaviour2 = 'BN120,TA1230';
function testStr(behaviour,string) {
return behaviour.includes(string);
}
console.log(testStr(behaviour1,string)) // gives true
console.log(testStr(behaviour2,string)) // gives false

isValidInput(behaviour, string) {
var array = behaviour.split(",");
var flag = 0;
for(var i = 0;i< array.length;i++){
var now = array[i];
var _flag = 1;
if (now.length == string.length) {
for (var j = 0; j < now.length; j++) {
if (now.charAt(j) == '*') {
continue;
}
if (now.charAt(j) != string.charAt(j)) {
_flag = 0;
}
}
flag |= _flag;
}
}
return flag;
}

Try modify your behaviour to RegExp:
function checkFn(testStr) {
var behaviour = '(BN...)|(TA....)'
var r = new RegExp('^(' + behaviour + ')$')
return r.test(testStr)
}
checkFn('BN123') // true
checkFn('BN12') // false
checkFn('BN1234') // false
checkFn('TA1234') // true
checkFn('TA123') // false
checkFn('TA12345') // false
Or use this fn:
function checkFn(testStr) {
var behaviour = 'BN***,TA****'
behaviour = behaviour
.split(',')
.reduce((r, el) => {
r.push('(' + el.replace(/\*/g, '.') + ')')
return r
}, [])
.join('|')
var r = new RegExp('^('+behaviour+')$')
return r.test(testStr)
}

Get function parameter length including default params

If you make use of the Function.length property, you get the total amount of arguments that function expects.
However, according to the documentation (as well as actually trying it out), it does not include Default parameters in the count.
This number excludes the rest parameter and only includes parameters before the first one with a default value
- Function.length
Is it possible for me to somehow get a count (from outside the function) which includes Default parameters as well?

Maybe you can parse it yourself, something like:
function getNumArguments(func) {
var s = func.toString();
var index1 = s.indexOf('(');
var index2 = s.indexOf(')');
return s.substr(index1 + 1, index2 - index1 - 1).split(',').length;
}
console.log(getNumArguments(function(param1, param3 = 'test', ...param2) {})); //3

Copying my answer over to here from a duplicate question:
Well, it's a bit of a mess but I believe this should cover most edge cases.
It works by converting the function to a string and counting the commas, but ignoring commas that are in strings, in function calls, or in objects/arrays. I can't think of any scenarios where this won't return the proper amount, but I'm sure there is one, so this is in no way foolproof, but should work in most cases.
UPDATE: It's been pointed out to me that this won't work for cases such as getNumArgs(a => {}) or getNumArgs(function(a){}.bind(null)), so be aware of that if you try to use this.
function getNumArgs(func) {
var funcStr = func.toString();
var commaCount = 0;
var bracketCount = 0;
var lastParen = 0;
var inStrSingle = false;
var inStrDouble = false;
for (var i = 0; i < funcStr.length; i++) {
if (['(', '[', '{'].includes(funcStr[i]) && !inStrSingle && !inStrDouble) {
bracketCount++;
lastParen = i;
} else if ([')', ']', '}'].includes(funcStr[i]) && !inStrSingle && !inStrDouble) {
bracketCount--;
if (bracketCount < 1) {
break;
}
} else if (funcStr[i] === "'" && !inStrDouble && funcStr[i - 1] !== '\\') {
inStrSingle = !inStrSingle;
} else if (funcStr[i] === '"' && !inStrSingle && funcStr[i - 1] !== '\\') {
inStrDouble = !inStrDouble;
} else if (funcStr[i] === ',' && bracketCount === 1 && !inStrSingle && !inStrDouble) {
commaCount++;
}
}
// Handle no arguments (last opening parenthesis to the last closing one is empty)
if (commaCount === 0 && funcStr.substring(lastParen + 1, i).trim().length === 0) {
return 0;
}
return commaCount + 1;
}
Here are a few tests I tried it on: https://jsfiddle.net/ekzuvL0c/

Here is a function to retrieve the 'length' of a function (expression or object) or an arrow function expression (afe). It uses a regular expression to extract the arguments part from the stringified function/afe (the part between () or before =>) and a regular expression to cleanup default values that are strings. After the cleanups, it counts the comma's, depending on the brackets within the arguments string.
Note This will always be an approximation. There are edge cases that won't be covered. See the tests in this Stackblitz snippet
const determineFnLength = fnLenFactory();
console.log(`fnTest.length: ${determineFnLength(fnTest)}`);
function fnTest(a,
b,
c = 'with escaped \' quote and, comma',
d = "and double \" quotes, too!" ) { console.log(`test123`); }
function fnLenFactory() {
const fnExtractArgsRE = /(^[a-z_](?=(=>|=>{)))|((^\([^)].+\)|\(\))(?=(=>|{)))/g;
const valueParamsCleanupRE = /(?<=[`"'])([^\`,].+?)(?=[`"'])/g;
const countArgumentsByBrackets = params => {
let [commaCount, bracketCount, bOpen, bClose] = [0, 0, [...`([{`], [...`)]}`]];
[...params].forEach( chr => {
bracketCount += bOpen.includes(chr) ? 1 : bClose.includes(chr) ? -1 : 0;
commaCount += chr === ',' && bracketCount === 1 ? 1 : 0; } );
return commaCount + 1; };
const extractArgumentsPartFromFunction = fn => {
let fnStr = fn.toString().replace(RegExp(`\\s|function|${fn.name}`, `g`), ``);
fnStr = (fnStr.match(fnExtractArgsRE) || [fn])[0]
.replace(valueParamsCleanupRE, ``);
return !fnStr.startsWith(`(`) ? `(${fnStr})` : fnStr; };
return (func, forTest = false) => {
const params = extractArgumentsPartFromFunction(func);
const nParams = params === `()` ? 0 : countArgumentsByBrackets(params);
return forTest ? [params, nParams] : nParams;
};
}

splitting a string based on AND OR logic in javascript

My problem is to split a string which contains a logical operation.
For example, here is my sample string:
var rule = "device2.temperature > 20 || device2.humidity>68 && device3.temperature >10"
I need to parse that string in a way that I can easily operate my logic and I am not sure which approach would be better.
PS: Please keep in mind that those rule strings can have 10 or more different condition combinations, like 4 ANDs and 6 ORs.

Assuming no parentheses, I might go with something like this (JavaScript code):
function f(v,op,w){
var ops = {
'>': function(a,b){ return a > b; },
'<': function(a,b){ return a < b; },
'||': function(a,b){ return a || b; },
'&&': function(a,b){ return a && b; },
'==': function(a,b){ return a == b;}
}
if (ops[op]){
return ops[op](v,w);
} else alert('Could not recognize the operator, "' + op + '".');
}
Now if you can manage to get a list of expressions, you can evaluate them in series:
var exps = [[6,'>',7],'||',[12,'<',22], '&&', [5,'==',5]];
var i = 0,
result = typeof exps[i] == 'object' ? f(exps[i][0],exps[i][1],exps[i][2]) : exps[i];
i++;
while (exps[i] !== undefined){
var op = exps[i++],
b = typeof exps[i] == 'object' ? f(exps[i][0],exps[i][1],exps[i][2]) : exps[i];
result = f(result,op,b);
i++;
}
console.log(result);

If you are absolutely sure that the input is always going to be valid JavaScript
var rule = "device2.temperature > 20 || device2.humidity>68 && device3.temperature >10"
var rulePassed = eval(rule);
Keep in mind that in most cases "eval" is "evil" and has the potential to introduce more problems than it solves.

function parse(rule){
return Function("ctx", "return("+rule.replace(/[a-z$_][a-z0-9$_\.]*/gi, "ctx.$&")+")");
}
a little bit better than eval, since it will most likely throw errors, when sbd. tries to inject some code.
Because it will try to access these properties on the ctx-object instead of the window-object.
var rule = parse("device2.temperature > 20 || device2.humidity>68 && device3.temperature >10");
var data = {
device2: {
temperature: 18,
humidity: 70
},
device3: {
temperature: 15,
humidity: 75
}
};
console.log( rule.toString() );
console.log( rule(data) );

Overkill:
beware, not fully tested. may still contain errors
And, code doesn't check wether syntax is valid, only throws on a few obvious errors.
var parse = (function(){
function parse(){
var cache = {};
//this may be as evil as eval, so take care how you use it.
function raw(v){ return cache[v] || (cache[v] = Function("return " + v)) }
//parses Strings and converts them to operator-tokens or functions
function parseStrings(v, prop, symbol, number, string){
if(!prop && !symbol && !number && !string){
throw new Error("unexpected/unhandled symbol", v);
}else{
var w;
switch(prop){
//keywords
case "true":
case "false":
case "null":
w = raw( v );
break;
}
tokens.push(
w ||
~unary.indexOf(prop) && v ||
prop && parse.fetch(v) ||
number && raw( number ) ||
string && raw( string ) ||
symbol
);
}
}
var tokens = [];
for(var i = 0; i < arguments.length; ++i){
var arg = arguments[i];
switch(typeof arg){
case "number":
case "boolean":
tokens.push(raw( arg ));
break;
case "function":
tokens.push( arg );
break;
case "string":
//abusing str.replace() as kind of a RegEx.forEach()
arg.replace(matchTokens, parseStrings);
break;
}
}
for(var i = tokens.lastIndexOf("("), j; i>=0; i = tokens.lastIndexOf("(")){
j = tokens.indexOf(")", i);
if(j > 0){
tokens.splice(i, j+1-i, process( tokens.slice( i+1, j ) ));
}else{
throw new Error("mismatching parantheses")
}
}
if(tokens.indexOf(")") >= 0) throw new Error("mismatching parantheses");
return process(tokens);
}
//combines tokens and functions until a single function is left
function process(tokens){
//unary operators like
unary.forEach(o => {
var i = -1;
while((i = tokens.indexOf(o, i+1)) >= 0){
if((o === "+" || o === "-") && typeof tokens[i-1] === "function") continue;
tokens.splice( i, 2, parse[ unaryMapping[o] || o ]( tokens[i+1] ));
}
})
//binary operators
binary.forEach(o => {
for(var i = tokens.lastIndexOf(o); i >= 0; i = tokens.lastIndexOf(o)){
tokens.splice( i-1, 3, parse[ o ]( tokens[i-1], tokens[i+1] ));
}
})
//ternary operator
for(var i = tokens.lastIndexOf("?"), j; i >= 0; i = tokens.lastIndexOf("?")){
if(tokens[i+2] === ":"){
tokens.splice(i-1, 5, parse.ternary(tokens[i-1], tokens[i+1], tokens[i+3] ));
}else{
throw new Error("unexpected symbol")
}
}
if(tokens.length !== 1){
throw new Error("unparsed tokens left");
}
return tokens[0];
}
var unary = "!,~,+,-,typeof".split(",");
var unaryMapping = { //to avoid collisions with the binary operators
"+": "plus",
"-": "minus"
}
var binary = "**,*,/,%,+,-,<<,>>,>>>,<,<=,>,>=,==,!=,===,!==,&,^,|,&&,||".split(",");
var matchTokens = /([a-z$_][\.a-z0-9$_]*)|([+\-*/!~^]=*|[\(\)?:]|[<>&|=]+)|(\d+(?:\.\d*)?|\.\d+)|(["](?:\\[\s\S]|[^"])+["]|['](?:\\[\s\S]|[^'])+['])|\S/gi;
(function(){
var def = { value: null };
var odp = (k,v) => { def.value = v; Object.defineProperty(parse, k, def) };
unary.forEach(o => {
var k = unaryMapping[o] || o;
k in parse || odp(k, Function("a", "return function(ctx){ return " + o + "(a(ctx)) }"));
})
//most browsers don't support this syntax yet, so I implement this manually
odp("**", (a,b) => (ctx) => Math.pow(a(ctx), b(ctx)));
binary.forEach(o => {
o in parse || odp(o, Function("a,b", "return function(ctx){ return a(ctx) "+o+" b(ctx) }"));
});
odp("ternary", (c,t,e) => ctx => c(ctx)? t(ctx): e(ctx));
odp("fetch", key => {
var a = key.split(".");
return ctx => {
//fetches a path, like devices.2.temperature
//does ctx["devices"][2]["temperature"];
for(var i=0, v = ctx /*|| window*/; i<a.length; ++i){
if(v == null) return void 0;
v = v[a[i]];
}
return v;
}
});
/* some sugar */
var aliases = {
"or": "||",
"and": "&&",
"not": "!"
}
for(var name in aliases) odp(name, parse[aliases[name]]);
})();
return parse;
})();
and your code:
var data = {
device2: {
temperature: 18,
humidity: 70
},
device3: {
temperature: 15,
humidity: 75
}
};
//you get back a function, that expects the context to work on (optional).
//aka. (in wich context/object is `device2` defined?)
var rule = parse("device2.temperature > 20 || device2.humidity>68 && device3.temperature >10");
console.log("your rule resolved:", rule(data));
sugar:
var rule1 = parse("device2.temperature > 20");
var rule2 = parse("device2.humidity>68 && device3.temperature >10");
//partials/combining rules to new ones
//only `and` (a && b), `or` (a || b), `plus` (+value), `minus` (-value) and 'not', (!value) have named aliases
var rule3 = parse.or(rule1, rule2);
//but you can access all operators like this
var rule3 = parse['||'](rule1, rule2);
//or you can combine functions and strings
var rule3 = parse(rule1, "||", rule2);
console.log( "(", rule1(data), "||", rule2(data), ") =", rule3(data) );
//ternary operator and Strings (' and " supported)
var example = parse(rule1, "? 'device2: ' + device2.temperature : 'device3: ' + device3.temperature");
console.log( example(data) )
What else to know:
Code handles operator precedence and supports round brackets
If a Path can't be fetched, it the particular function returns undefined (no Errors thrown here)
Access to Array-keys in the paths: parse("devices.2.temperature") fetches devices[2].temperature
not implemented:
parsing Arrays and parsing function-calls and everything around value modification. This engine does some computation, it expects some Value in, and gives you a value out. No more, no less.

all valid combinations of n-pair of parenthesis

I am learning js now..
I am trying to write a simple js programme..
what I am trying to do is to print all valid combinations of n-pair
of parenthesis(properly opened and closed)
eg (), (()()),(())
i have written the logic can you tell me whether its correct or not
https://jsfiddle.net/e7mcp6xb/
module.exports = Parentheses = (function() {
var _isParenthesesMatch = function(str) {
var parentheses = str.length;
var rightParentheses = '(';
var leftParentheses = ')';
var rightCount = 0;
var leftCount = 0;
for(i=0;i<=str.length;i++){
if(rightParentheses == str.charAt(i))
{
rightCount++;
}
else if(leftParentheses == str.charAt(i))
{
leftCount++;
}
}
if(rightCount == leftCount){
return true;
}
else(rightCount != leftCount){
return false;
}
}
}());

The check is wrong, but You can fix it easily: In each step of the for loop the number of opening parenthesis cannot be smaller than the number of closing ones:
if (rightCount < leftCount)
return false;
The whole function should look like this:
function(str) {
var rightParentheses = '(';
var leftParentheses = ')';
var rightCount = 0;
var leftCount = 0;
for (var i = 0; i <= str.length; i++) {
if (rightParentheses == str.charAt(i))
rightCount++;
else if (leftParentheses == str.charAt(i))
leftCount++;
if (rightCount < leftCount)
return false;
}
return rightCount == leftCount;
}
If You'd like to generate all valid strings, you can use this function:
function nPair(n) {
if (n == 0)
return [""];
var result = [];
for (var i = 0; i < n; ++i) {
var lefts = nPair(i);
var rights = nPair(n - i - 1);
for (var l = 0; l < lefts.length; ++l)
for (var r = 0; r < rights.length; ++r)
result.push("(" + lefts[l] + ")" + rights[r]);
}
return result;
}
// result of nPair(3):
// ["()()()", "()(())", "(())()", "(()())", "((()))"]

Try this, i have modified your code a little bit. Modification and its explanation is marked in comments.
module.exports = Parentheses = (function() {
var _isParenthesesMatch = function(str) {
var parentheses = str.length;
var rightParentheses = '(';
var leftParentheses = ')';
var count=0;
for(i=0;i<str.length;i++){
//this is to check valid combination start always from ( and end with )
if(str.charAt(0)==rightParentheses && str.length-1==leftParentheses)
{
if(rightParentheses == str.charAt(i))
{
count++; //this will calculate how many times rightParentheses is present & increment count by 1
}
else if(leftParentheses == str.charAt(i))
{
count--; //this will simply decrement count to match valid sequence
}
}
if(count==0){
return true;
}
}
}());

Your function is wrong, try checking if left and right parenthesis and balanced:
function isValid(str){
var stripedStr = str.replace(/[^\(\)]+/g, '');
return stripedStr.split('').reduce(function(a, b){
return a > -1 ? b === '(' ? a + 1 : a - 1 : -1;
}, 0) === 0;
}
stripedStr - use replace() to remove any characters that are not ( or ).
split('') - returns an array so we can use reduce.
reduce() - applies a function against an accumulator and each value of the array (from left-to-right) has to reduce it to a single value.
The reduce starts with 0 as initial value and in the reduce function we count parenthesis
(+1 for (, -1 for ) )
Our string is valid if our counter never goes below 0 and we end up with 0.
You can write the reduce function like this too:
function(previousValue, currentValue){
if (previousValue > -1){
if (currentValue === '('){
return previousValue + 1;
} else {
return previousValue - 1;
}
}
return -1;
}
This is equivalent to:
function(a, b){
return a > -1 ? b === '(' ? a + 1 : a - 1 : -1;
}

It is wrong, because your function will return true for this example ))(( or this ())(()

Check SSL certificate Expiration Date

I need to check local computer's SSl certificate expiry DATE and compare it with current date and notify user that his/her certificate is going to expire in X days. All this I need to do in JavaScript.

Your certificate should look like this:
-----BEGIN CERTIFICATE-----
MIIGoDCCBIigAwIBAgIJAICRY3cWdgK1MA0GCSqGSIb3DQEBCwUAMIGeMQswCQYD
VQQGEwJCRzERMA8GA1UECAwIQnVsZ2FyaWExDjAMBgNVBAcMBVNvZmlhMQ8wDQYD
..
ud5Nja8+xycA/Jk7bSvB1jJjpc3oL0G9j0HOcxqQKd4e1IQXuss5V7FnQxSOVCq4
GVK0r3LkAxtl/EGmQC1DRlHAUWg=
-----END CERTIFICATE-----
You need to strip the -----BEGIN CERTIFICATE----- header and the -----END CERTIFICATE----- trailer from the certificate data, the rest is a Base64 encoded byte array.
You need to decode it to an array of bytes (in this example represented as array of number, where each number represents a byte - number between 0 and 255 inclusive).
That byte array is a DER encoded ASN.1 structure as defined in RFC-5280.
The below example will parse the content of the certificate after the -----BEGIN CERTIFICATE----- and -----END CERTIFICATE----- traile has already been stripped.
Usage:
var pem =
"MIIGijCCBXKgAwIBAgIQEpI/gkvDS6idH2m2Zwn7ZzANBgkqhkiG9w0BAQsFADCB\n"
...
+"VQ+o34uWo7z19I8eXWSXN6P+Uj1OvHn8zNM1G/ddjQXBwMvzwwJEdVBhdK1uQw==\n";
var bytes = fromBase64(pem);
var validity = getValidity(bytes);
var notBefore = validity.notBefore;
var notAfter = validity.notAfter;
var now = new Date();
if ( notBefore.getTime() < now.getTime()
&& now.getTime() < notAfter.getTime())
{
// Certificate is withing its validity days
} else {
// Certificate is either not yet valid or has already expired.
}
Parsing:
var TYPE_INTEGER = 0x02;
var TYPE_SEQUENCE = 0x10;
var TYPE_UTC_TIME = 0x17;
var TYPE_GENERALIZED_TIME = 0x18;
function subArray(original, start, end) {
var subArr = [];
var index = 0;
for (var i = start; i < end; i++) {
subArr[index++] = original[i];
}
return subArr;
}
function getDigit(d) {
switch (d) {
default:
case 0x30: case '0': return 0;
case 0x31: case '1': return 1;
case 0x32: case '2': return 2;
case 0x33: case '3': return 3;
case 0x34: case '4': return 4;
case 0x35: case '5': return 5;
case 0x36: case '6': return 6;
case 0x37: case '7': return 7;
case 0x38: case '8': return 8;
case 0x39: case '9': return 9;
}
}
function enterTag(bytes, start, requiredTypes, name) {
if (start + 1 > bytes.length) {
throw new Error("Too short certificate input");
}
var typeByte = bytes[start ] & 0x0FF;
var lenByte = bytes[start +1] & 0x0FF;
var type = typeByte & 0x1F;
var len = lenByte;
var index = start + 2;
if (requiredTypes.length > 0 && requiredTypes.indexOf(type) == -1) {
throw new Error("Invalid type");
}
var lengthOfLength = 0;
if (len > 0x07F) {
lengthOfLength = len & 0x7F;
len = 0;
for (var i =0; i < lengthOfLength && index < bytes.length; i++) {
len = (len << 8 ) | (bytes[index] & 0x00FF);
index++;
}
}
if (index >= bytes.length) {
throw new Error("Too short certificate input");
}
return {index: index, type: type, length: len}
}
function processTag(bytes, start, requiredTypes, name) {
var result = enterTag(bytes, start, requiredTypes, name);
var index = result.index + result.length;
if (index >= bytes.length) {
throw new Error("Too short certificate input");
}
var valueStart = result.index;
var valueEnd = result.index + result.length;
var value = subArray(bytes, valueStart, valueEnd);
return { index: index, type: result.type, value: value};
}
function readDate(bytes, start, name) {
var date = new Date();
var result = processTag(bytes, start,
[TYPE_UTC_TIME, TYPE_GENERALIZED_TIME], name);
var index, year;
if (result.type == 0x17) { // UTCTime
if (result.value.length < 12) {
throw new Error("Invalid type");
}
var yearHigh = getDigit(result.value[0]);
var yearLow = getDigit(result.value[1]);
var year2Digits = (yearHigh * 10 ) + (yearLow)
if (year2Digits >= 50) {
year = 1900 + year2Digits;
} else {
year = 2000 + year2Digits;
}
index = 2;
} else if (result.type = 0x18) { // GeneralizedTime
if (result.value.length < 14) {
throw new Error("Invalid type");
}
var year1 = getDigit(result.value[0]);
var year2 = getDigit(result.value[1]);
var year3 = getDigit(result.value[2]);
var year4 = getDigit(result.value[3]);
year = (year1 * 1000) + (year2 * 100) + (year3*10) + year4;
index = 4;
}
var monthHigh = getDigit(result.value[index++]);
var monthLow = getDigit(result.value[index++]);
var dayHigh = getDigit(result.value[index++]);
var dayhLow = getDigit(result.value[index++]);
var hourHigh = getDigit(result.value[index++]);
var hourLow = getDigit(result.value[index++]);
var minuteHigh = getDigit(result.value[index++]);
var minuteLow = getDigit(result.value[index++]);
var secondHigh = getDigit(result.value[index++]);
var secondLow = getDigit(result.value[index]);
var month = (monthHigh * 10) + monthLow;
var day = (dayHigh * 10) + dayhLow;
var hour = (hourHigh * 10) + hourLow;
var minute = (minuteHigh * 10) + minuteLow;
var second = (secondHigh * 10) + secondLow;
if (month < 1 || month > 12) {
throw new Error("Invalid month");
}
if (day < 1 || day > 31) {
throw new Error("Invalid day");
}
if (hour < 0 || hour > 24) {
throw new Error("Invalid hour");
}
if (minute < 0 || minute > 59) {
throw new Error("Invalid minute");
}
if (second < 0 || second > 59) {
throw new Error("Invalid second ");
}
date.setUTCFullYear(year);
date.setUTCMonth(month-1);
date.setUTCDate(day);
date.setUTCHours(hour);
date.setUTCMinutes(minute);
date.setUTCSeconds(second);
return {
index: result.index,
type: result.type,
length: result.length,
value: result.value,
date: date
};
}
function getValidity(bytes) {
if (bytes == null || bytes.length <= 0) {
return null;
}
var index = 0;
index = enterTag(bytes, index, [TYPE_SEQUENCE], "Certificate").index;
index = enterTag(bytes, index, [TYPE_SEQUENCE], "TBSCertificate").index;
var result = processTag(bytes, index, [0x00, 0x02],
"Version or SerialNumber");
if (result.type == 0) {
index = result.index;
result = processTag(bytes, index, [TYPE_INTEGER], "SerialNumber")
}
index = result.index;
result = processTag(bytes, index, [TYPE_SEQUENCE],
"Signature AlgorithmIdentifier");
index = result.index;
result = processTag(bytes, index, [], "Issuer Name");
index = result.index;
index = enterTag(bytes, index, [TYPE_SEQUENCE], "Validity").index;
result = readDate(bytes, index, "Not Before");
var notBefore = result.date;
index = result.index;
result = readDate(bytes, index, "Not After");
var notAfter = result.date;
return {notBefore: notBefore, notAfter: notAfter};
}
function getNextBase64Chr(str, index, equalSignReceived, alpha) {
var chr = null;
var code = 0;
var padding = equalSignReceived;
while (index < str.length) {
chr = str.charAt(index);
if (chr == " " || chr == "\r" || chr == "\n" || chr == "\t") {
index++;
continue;
}
if (chr == "=") {
padding = true;
} else {
if (equalSignReceived) {
throw new Error("Invalid Base64 Endcoding.");
}
code = alpha.indexOf(chr);
if (code == -1) {
throw new Error("Invalid Base64 Encoding .");
}
}
break;
}
return { character: chr, code: code, padding: padding, nextIndex: ++index};
}
function fromBase64(str) {
var alpha = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
var value = [];
var index = 0;
var destIndex = 0;
var padding = false;
while (true) {
var first = getNextBase64Chr(str, index, padding, alpha);
var second = getNextBase64Chr(str, first .nextIndex, first .padding, alpha);
var third = getNextBase64Chr(str, second.nextIndex, second.padding, alpha);
var fourth = getNextBase64Chr(str, third .nextIndex, third .padding, alpha);
index = fourth.nextIndex;
padding = fourth.padding;
// ffffffss sssstttt ttffffff
var base64_first = first.code == null ? 0 : first.code;
var base64_second = second.code == null ? 0 : second.code;
var base64_third = third.code == null ? 0 : third.code;
var base64_fourth = fourth.code == null ? 0 : fourth.code;
var a = (( base64_first << 2 ) & 0xFC ) | ((base64_second >> 4) & 0x03);
var b = (( base64_second << 4 ) & 0xF0 ) | ((base64_third >> 2) & 0x0F);
var c = (( base64_third << 6 ) & 0xC0 ) | ((base64_fourth >> 0) & 0x3F);
value [destIndex++] = a;
if (!third.padding) {
value [destIndex++] = b;
} else {
break;
}
if (!fourth.padding) {
value [destIndex++] = c;
} else {
break;
}
if (index >= str.length) {
break;
}
}
return value;
}
Used resources:
A Layman's Guide to a Subset of ASN.1, BER, and DER
Encoding of ASN.1 UTC Time and GeneralizedTime
RFC-5280

The only available option so far is forge - https://github.com/digitalbazaar/forge/blob/master/README.md or some sort of custom extension for the client.
Client side does not know nothing about other than DOM elements thus it cannot inspect SSL layer.
More on this Within a web browser, is it possible for JavaScript to obtain information about the SSL Certificate being used for the current page?

This is not possible from the client, but you could do something like this with node / shell combo.
Assuming you have access to the server the cert is running on you could do something like this on the host:
var execSync = require('child_process').execSync
var cmd = "echo | openssl s_client -connect 127.0.0.1:443 2>/dev/null | openssl x509 -noout -dates"
var stdout = execSync(cmd).toString()
// "notBefore=Feb 16 15:33:00 2017 GMT\nnotAfter=May 17 15:33:00 2017 GMT"
From there you could parse the dates reported by stdout and write them to a public resource or json file so they are readable from the client, and from there do your date comparison.