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What I'm trying to do is the following:
SUM(Sales) + SUM(Revenue)
or MIN(Sales) + SUM(Revenue).
What I want is the first calculation. So for 1), the result "SUM" will be given, and for 2) the result "MIN" will be given.
I've tried this for if statements but it's either impossible, or incredibly difficult to do that way. Could anyone guide me on potentially a RegEx way of doing this?
What I tried in if statements:
function hasFormula(formulaToLower) {
// formulaToLower could equal "SUM(Sales) + SUM(Revenue)" etc
// could also equal "SUM(Sales) + MIN(Revenue)" - this will return MIN, but it return SUM.
if (formulaToLower.indexOf('sum') !== -1) {
return "SUM";
}
if (formulaToLower.indexOf('min') !== -1) {
return "MIN";
}
}
Obviously though, this will bring out MIN first, even if it's found second, and so on...
You can use a regexp that allows all the combinations you want. The matches will be returned in the correct order if you use the global modifier, or only the first one will be returned if you do not:
var matcher = /SUM|MIN|MAX|AVG/;
var str1 = 'SUM(Sales) + SUM(Revenue)';
var str2 = 'MIN(Sales) + SUM(Revenue)';
console.log(str1.match(matcher)[0]) // SUM
console.log(str2.match(matcher)[0]) // MIN
*The [0] part takes the first element in the array of results returned by match.
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I created button that is generate a random number every time , but in the console log it shows it like this:
small project i have been working on during course of javascript
I tried to make one array of random numbers and when it reach above 4 random numbers i will use Shift method to erase one. ( I also tried to use for loop )
What actually happen that is it kind of creates me new array inside of the orginal array
let randomArr = [];
if (randomArr.length >= 4) {
randomArr.shift();
lastNumbers.textContent -= randomArr + ",";
return randomArr;
} else {
randomArr.push(randomNumber);
// randomArr.length = randomArr;
lastNumbers.textContent += randomArr + ",";
// return randomArr;
}
Ty for helping!
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I came across this piece of code which checks if number of occurrences of an element in an array is greater than it is specified, and if yes it will remove the number:
function deleteNth(arr,x) {
var cache = {};
return arr.filter(function(n) {
cache[n] = (cache[n]||0) + 1;
return cache[n] <= x;
});
}
But I didn't understand the code from here: arr.filter(function(n){cache[n] = (cache[n]||0) + 1;return cache[n] <= x;});
Can anyone please explain in simple words what happens here and how does cache[n] part work.
Why is cache[n] incremented?
Thanks!
The arr.filter() begins by iterating over each item in the array and this case each item is represented by 'n'.
This item is then added to the empty object where 'n' is the key and the value is then incremented by one for each new item added to the object.
The return statement uses the cache to do a check of what 'n' values are less than or equal to x. If it returns false they are not added into the new array that is created. So if 'x' is 3 it will remove everything after the first three items from the array.
EDIT
Another way of writing the function which might make it more clear could be
function deleteNth(arr,x) {
return arr.filter((item, index) => {
if (index <= x) {
return item;
}
});
}
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I have an url that looks like this:
https://example.com/?category=123&dk=sports&dk=groupcompanyinsider&dk=local&lang=en
Is it possible to return every dk parameter separately? (no matter if there will be 1 or 5 dk parameters) so i would get separately sports, groupcompanyinsider, local.
If its not possible maybe there is a way to return all of them in one string like dk=sports&dk=groupcompanyinsiderlocal&dk=local ?
You can use the built-in javascript class URLSearchParams for this.
You can then transform this into the string you want with string concatenation and a foreach.
const url = "https://example.com/?category=123&dk=sports&dk=groupcompanyinsider&dk=local&lang=en";
var params = new URLSearchParams(url);
var result = "";
// concatenate individual values of the 'dk' query parameter
params.getAll('dk').forEach(function (item) {
result += '&dk=' + item;
});
result = result.substr(1); // remove starting '&' from the result;
console.log(result);
The result should contain your desired string.
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I recently came across this little problem to solve on a website, counting the number of vowels in a string. I succeeded using a switch statement, but when I looked at the authors solution they had used the following function.
function vowel_count(str1) {
var vowel_list = 'aeiouAEIOU';
var vcount = 0;
for (var x = 0; x < str1.length ; x++) {
if (vowel_list.indexOf(str1[x]) !== -1) {
vcount += 1;
}
}
return vcount;
}
alert(vowel_count("The quick brown fox"));
Can anyone please explain what exactly is happening in the if statement,
I can see the index of whatever string that is passed to the function is being used but why would the statement == or !== -1. I'm a bit confused as to how the function is checking the string.
Thanks in advance.
The indexOf() function returns the index of an element we're looking for in a given array. However, if the element is nowhere to be found in the array, indexOf() returns -1 instead.
So in your case:
if (vowel_list.indexOf(str1[x]) !== -1) {
means something like "if the current letter can be found in my list of vowels".
Does that make sense ?
The indexOf method returns the position of the first occurrence of a specified value in a string. It returns -1 if the value to search for never occurs.
JavaScript, like most programming languages, starts counting from 0.
"foo".indexOf('f'); is 0.
The function returns -1 if the value isn't found.
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Hello I really want to learn how to do something like this. If you go to a page for example it says http://example.net/search.html?catagory=food&includelevelone=true. I do not have access to php so it can only be HTML and Javascript/jQuery. Thanks in advance!
The part of the URL that is from the questionmark onwards is called a query string.
Here is a pure JavaScript function to parse the query string to obtain particular values:
function querystring(key)
{
var filter;
var value;
key = key.replace(/[\[]/, '\\\[').replace(/[\]]/, '\\\]');
filter = new RegExp('[\\?&]' + key + '=([^&#]*)');
value = filter.exec(window.location.search);
if(value == null)
{
return '';
}
else
{
return decodeURIComponent(value[1].replace(/\+/g, ' '));
}
}
You just pass in the query string key name you're interested in (as a string) and you get the value back (also as a string.) An example of how you could use the function:
alert('Category = ' + querystring('catagory'));
Everything behind the questionmark is a url parameter. every word left of an equal sign is the name of the parameter, everything right of an equal sign is the corresponding value. The name-value-pairs are divided by &-signs
Here are two pages i quickly googled that are about getting these parameters in JavaScript (wich is really not that hard):
http://code-tricks.com/get-url-parameters-using-javascript
http://ziemecki.net/content/javascript-parsing-url-parameters