How to remove spaces from an array? - javascript

I am attempting to print out several parts of an array as a string. However when I do print out the string, there are spaces before the commas which is giving me some trouble.
Here is some example code:
var Arr = [];
var foo = "Hello";
var voo = "World";
if (foo != null) {
Arr.push(foo);
}
if (voo != null) {
Arr.push(voo);
}
console.log(Arr.join(', '));
How can one print out said string without the spaces before the commas?
EDIT: I should clarify that in my actual code, I am pushing values from a tab-delimited text file into an array.


Your code should print the correct output. (Fixing the obvious typos that were in your original post). You likely have an issue with your original code (A space after what is stored in the variable foo).
var arr = [];
var foo = "Hello";
var voo = "World";
if (foo != null){
arr.push(foo);
}
if (voo != null){
arr.push(voo);
}
console.log(arr.join(', '));


Fixing all the minor errors in your code produces:
var myArray = [];
var foo = "Hello";
var voo = "World";
if (foo != null) {
myArray.push(foo);
}
if (voo != null) {
myArray.push(voo);
}
console.log(myArray.join(', '));
A brief summary:
Array is a built-in type - don’t use it as a variable name.
!- is not a valid operator, did you mean !=?
: at the end of a line is invalid syntax, did you mean ;?
console.println() doesn’t exist, did you mean console.log()?


Basically, when you joined the array, you were specifying a space after the comma, so why not remove it like below:
Arr.join(',');


So, I am assuming the spaces you mentioned are the tab spaces based on the recent question edit.
You can use regex to replace the '\t' with ' ' single space or no space as required.
foo.replace(/\t/g, "");
And if you just want to concat two strings, I wonder why you cannot just use the '+' operator with the comma rather than creating an auxiliary array to store them?


you can remove commas like this and print without space
console.log(Arr.join(''));
if you want keep space
console.log(Arr.join(' '));
3.want tab space
console.log(Arr.join('\t'));

Related

How to replace strings and get what I need in this case?

I am trying to replace a string with two sets of patterns. For example,
var pattern1 = '12345abcde/'; -> this is dynamic.
var myString = '12345abcde/hd123/godaddy_item'
my end goal is to get the value between two slashes which is hd123
I have
var stringIneed = myString.replace(pattern1, '').replace('godaddy_item','');
The above codes work but I think there is more elegant solution. Can anyone help me out on this? Thanks a lot!
UPDATE:
To be more clear, the pattern is per environement string. For example,
pattern1 could be something like:
https://myproject-development/item on development environment.
and
https://myproject/item on Production
myString could usually be like
https://myproject/item/hd123/godaddy_item
or
https://myproject-development/item/hd123/godaddy_item
and I need to get 'hd123' in my case.

I'd strongly suggest not using regular expressions for this, especially when simple String and Array methods will easily suffice and be far more understandable, such as:
// your question shows you can anticipate the sections you
// don't require, so put both/all of those portions into an
// array:
var unwanted = ['12345abcde', 'godaddy_item'],
// the string you wish to find the segment from:
myString = '12345abcde/hd123/godaddy_item',
// splitting the String into an array by splitting on the '/'
// characters, filtering that array using an arrow function
// in which the section is the current array-element of the
// array over which we're iterating; and here we keep those
// sections which are not found in the unwanted Array (the index
// an element not found in an Array is returned as -1):
desired = myString.split('/').filter(section => unwanted.indexOf(section) === -1);
console.log(desired); // ["hd123"]
Avoiding Arrow functions, for browsers not supporting ES6 (and having removed the code comments):
var unwanted = ['12345abcde', 'godaddy_item'],
myString = '12345abcde/hd123/godaddy_item',
desired = myString.split('/').filter(function (section) {
return unwanted.indexOf(section) === -1;
});
console.log(desired); // ["hd123"]
Or:
// the string to start with and filter:
var myString = '12345abcde/hd123/godaddy_item',
// splitting the string by the '/' characters and keeping those whose
// index is greater than 0 (so 'not the first') and also less than the
// length of the array-1 (since JS arrays are zero-indexed while length
// is 1-based):
wanted = myString.split('/').filter((section, index, array) => index > 0 && index < array.length - 1);
console.log(wanted); // ["hd123"]
JS Fiddle demo
If, however, the requisite string to be found is always the penultimate portion of the supplied string, then we can use Array.prototype.filter() to return only that portion:
var myString = '12345abcde/hd123/godaddy_item',
wanted = myString.split('/').filter((section, index, array) => index === array.length - 2);
console.log(wanted); // ["hd123"]
JS Fiddle demo.
References:
Array.prototype.filter().
Arrow functions.
String.prototype.split().

You can use
.*\/([^\/]+)\/.*$
Regex Demo
JS Demo
var re = /.*\/([^\/]+)\/.*$/g;
var str = '12345abcde/hd123/godaddy_item';
while ((m = re.exec(str)) !== null) {
document.writeln("<pre>" + m[1] + "</br>" + "</pre>");
}

You can easily do something like this:
myString.split('/').slice(-2)[0]
This will return the item directly, in simple most way.
var myString = 'https://myproject/item/hd123/godaddy_item';
console.log(myString.split('/').slice(-2)[0]); // hd123
myString = 'https://myproject-development/item/hd123/godaddy_item';
console.log(myString.split('/').slice(-2)[0]); // hd123

Try using match() as shown below:
var re = /\/(.*)\//;
var str = '12345abcde/hd123/godaddy_item';
var result = str.match(re);
alert(result[1]);

To say that David's answer will "easily suffice and be far more understandable" is a matter of opinion - this regex option (which includes building up the expression from variables) really couldn't be much simpler:
var pathPrefix = '12345abcde/'; //dynamic
var pathToTest = '12345abcde/hd123/godaddy_item';
var pattern = new RegExp(pathPrefix + '(.*?)\/')
var match = pattern.exec(pathToTest);
var result = (match != null && match[1] != null ? '[' + match[1] + ']' : 'no match was found.'); //[hd123]

Failing test as a string

I am running through some exercises and run into this on codewars. Its a simple exercise with Instructions to create a function called shortcut to remove all the lowercase vowels in a given string.
Examples:
shortcut("codewars") // --> cdwrs
shortcut("goodbye") // --> gdby
I am newbie so I thought up this solution. but it doesn't work and I have no idea why
function shortcut(string){
// create an array of individual characters
var stage1 = string.split('');
// loop through array and remove the unneeded characters
for (i = string.length-1; i >= 0; i--) {
if (stage1[i] === "a"||
stage1[i] === "e"||
stage1[i] === "i"||
stage1[i] === "o"||
stage1[i] === "u") {
stage1.splice(i,1)
;}
};
// turn the array back into a string
string = stage1.join('');
return shortcut;
}
My gut is telling me that it will probably something to like split and join not creating "true" array's and strings.
I did it at first with a regex to make it a little more reusable but that was a nightmare. I would be happy to take suggestions on other methods of acheiving the same thing.

You are returning the function itself, instead of returning string

Using regex:
var str = 'codewars';
var regex = /[aeiou]/g;
var result = str.replace(regex, '');
document.write(result);

if interested in Regular Expression ;)
function shortcut(str) {
return str.replace(/[aeiou]/g, "");
}

Javascript Regex Search

I generated the following code through a website. What I am looking for is that the script scans through a text variable against a set of keywords, and if it finds any of the keywords, it passes it to a variable. And if two keywords are found, both are joined by a hyphen and passed to a variable. I also need to set the "var str" dynamically. For instance, "var str == VAR10." VAR10 will have a dynamic text to be searched for keywords.
var re = /Geo|Pete|Rob|Nick|Bel|Sam|/g;
var str = 'Sam maybe late today. Nick on call. ';
var m;
if ((m = re.exec(str)) !== null) {
if (m.index === re.lastIndex) {
re.lastIndex++;
}
}
In the above code, Sam and Nick are two keywords that I want hyphenated and passed to VAR10.

If two keywords are found, both are joined by a hyphen and passed to a
variable
Try this update to your original code for clarity:
var re = /Geo|Pete|Rob|Nick|Bel|Sam/g;
var str = 'Sam maybe late today. Nick on call. ';
var m;
var VAR10 = ""; // holds the names found
if ((m = re.exec(str)) !== null) {
var name1 = m;
if ((m = re.exec(str)) !== null) {
var name2 = m;
// Two names were found, so hyphenate them
// Assign name1 + "-" + name2 to the var that you want
VAR10 = name1 + "-" + name2;
} else {
// In the case only one name was found:
// Assign name1 to the var that you want
VAR10 = name1;
}
}
Note, change
var re = /Geo|Pete|Rob|Nick|Bel|Sam|/g;
to
var re = /Geo|Pete|Rob|Nick|Bel|Sam/g;
Here is an updated demo: http://jsfiddle.net/7zg2hnt6/1/

You can "capture" names with parenthesis:
/(Geo|Pete|Rob|Nick|Bel|Sam)/g
A sample: https://regex101.com/r/eK5hY2/1

To return the first two names found in hyphenated fashion:
str.match(re) . slice(0, 2) . join('-')
You have an extra | at the end of your regexp, which is likely to result in matches on an empty string. Remove it.
I also need to set the "var str" dynamically. For instance, "var str == VAR10." VAR10 will have a dynamic text to be searched for keywords.
var str == VAR10 is invalid syntax. I'll assume you mean var str = VAR10;. That's just a plain old variable assignment. All assignments in JS are "dynamic" by definition and happen at run-time. This would seem to have nothing to do with your specific problem.

Your code is almost doing what you want.
First you need to capture your matches, then join them.
http://jsfiddle.net/c6tjk21d/1/
var re = /(Geo|Pete|Rob|Nick|Bel|Sam)/g;
var str = 'Sam maybe late today. Nick on call. ';
var VAR10 = str.match(re).join('-')
console.log(VAR10);
I don't think you want to use exec because it maintains state and I've found it to be unintuitive. For example, in order to get more than one match with the code you've written, you'll need to loop through resulting on exec. Check out MDN for examples if you're interested. I almost always prefer match().

Replace double commas until there are some

I am trying to replace all double commas with ,null,
The problem is that i need to keep doing it while it is replacing it. I am thinking about adding a loop but is there any other more eficient alternative?
var test = "[1,2,,,3,4,,,,,,5,6]".replace(/,{2}/g, ",null,");
alert(test);
The result should be:
"[1,2,null,null,3,4,null,null,null,null,null,5,6]"
But is instead:
[1,2,null,,3,4,null,,null,,null,5,6]
So I would have to create a loop and do it until all double commas are done. Not sure if there is any other way?
As a side info, this is so that I can afterwards do:
var myArray = $.parseJSON(test);
Which currently it fails which I'm guessing that it's because it is not valid json.

Single regex:
"[AB,,,CD,,,,,,EF]".replace(/,(?=,)/g, ',null');
demo
Here we use the ?= lookahead to find 2 commas ("comma with a comma after it") but match and replace only the first.
Edit:
You seem to be interested in speed, here are some tests.

str.split(',').map(function(x) { return x ? x : 'null' }).join(',');
FIDDLE
splits the string by commas, then map() iterates and returns each value from the callback, and the ternary returns x (the value) if thruthy and the string 'null' if falsy, which an empty string is, then join it back together again.

You can do this:
var test = "[1,2,,,3,4,,,,,,5,6]".split(',').join(',|').replace(/\|,/g,"null,");
alert(test.replace(/\|/g,""));
It alerts:
[1,2,null,null,3,4,null,null,null,null,null,5,6]
Demo: http://jsfiddle.net/AmitJoki/Zuv38/

Not sure if regex could handle that without looping.
Alternative solution is to split is into an array: '1,2,,,3,4,,,,,,5,6'.split(','); and then loop through it and replace all empty strings with null and then join it back.
So, something like this:
var s = '1,2,,,3,4,,,,,,5,6';
var a = s.split(',');
for (var i = 0; i < a.length; i++) {
if (a[i] == "") {
a[i] = "null";
}
}
s = '[' + a.join(',') + ']';
See it here: http://jsfiddle.net/fVMLv/1/

Try this
var str = "1,2,,,3,4,,,,,,5,6";
str = str.split(',');
var strResult ='';
$(str).each(function(){
if(this==''){
strResult +='null,';
}
else{
strResult +=this+',';
}
});
strResult = strResult.substring(0,strResult.length-1);
alert(strResult);
DEMO

The problem is with the double commas occurring consecutively.
,,,, -> will be taken as 2 sets of double commas by that RegExp. So, result will be:-
,null,,null, -> note that the occurrence of another double comma in between is skipped, since the RegEx is greedy (2nd comma is already used, which is not used again together with 3rd comma. rather 3rd and 4th are used together).
var test = "[AB,,,CD,,,,,,EF]".replace(/,,/g, ",null,").replace(/,,/g, ",null,");
alert(test);
So, with this RegExp, calling it twice will fix this.

Remove special character from the starting of a string and search # symbol.in javascript

I want to remove special characters from the starting of the string only.
i.e, if my string is like {abc#xyz.com then I want to remove the { from the starting. The string shoould look like abc#xyz.com
But if my string is like abc{#xyz.com then I want to retain the same string as it is ie., abc{#xyz.com.
Also I want to check that if my string has # symbol present or not. If it is present then OK else show a message.

The following demonstrates what you specified (or it's close):
var pat = /^[^a-z0-9]*([a-z0-9].*?#.*?$)/i; //pattern for optional non-alphabetic start followed by alphabetic, followed by '#' somewhere
var testString = "{abc#xyz.com"; //Try with {abcxyz.com for alert
arr = pat.exec(testString);
var adjustedString;
if (arr != null) { adjustedString = arr[1]; } //The potentially adjustedString (chopped off non-alphabetic start) will be in capture group 1
else { adjustedString = ""; alert(testString + " does not conform to pattern"); }
adjustedString;

I have used two separate regex objects to achieve what you require .It checks for both the conditions in the string.I know its not very efficient but it will serve your purpose.
var regex = new RegExp(/(^{)/);
var regex1 = new RegExp(/(^[^#]*$)/);
var str = "abc#gmail.com";
if(!regex1.test(str)){
if(regex.test(str))
alert("Bracket found at the beginning")
else
alert("Bracket not found at the beginning")
}
else{
alert("doesnt contain #");
}
Hope this helps

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