Reading a line backwards - javascript

I'm using regular expression to count the total spaces in a line (first occurrence).
match(/^\s*/)[0].length;
However this reads it from the start to end, How can I read it from end to start.
Thanks

You can do this:
function reverse(str) {
return str.split('').reverse().join('');
}
To use it:
var str = 'Hello World';
alert(reverse(str));
How it works, we split the string by an empty character to turn it into an array, then we reverse the order of the array, then we join it all back together, using no character as the glue. So we get alerted dlroW olleH

Are you trying to find the number of trailing spaces on a line?
s.match(/\s*$/)[0].length;
Or last spaces found, even if there's something else trailing:
s.match(/(\s*)[^\s]*$/)[1].length

do you just want to know how many chars there is before the space? If so, does this not suit your needs.
var str = 'The quick brown fox jumps';
var first = str.indexOf(' ');
var last = str.lastIndexOf(' ');
alert('first space is at: ' + first + ' and last space is at: ' + last);

I'm using regular expression to count the total spaces in a line
Then why do you care about which way it counts? "aaa" contains 3 a's whether I start from the first or last one. 3 is still 3...

Related

Add a space to UK Postcode in correct place Javascript

I am trying to write a basic function that will allow me to add a space to UK postcodes where the spaces have been removed.
UK postcodes always have a space before the final digit of the postcode string.
Some examples with no spacing and with correct spacing:
CB30QB => CB3 0QB
N12NL => N1 2NL
OX144FB => OX14 4FB
To find the final digit in the string I am regex /\d(?=\D*$)/g and the Javascript I have in place currently is as follows:
// Set the Postcode
var postCode = "OX144FB";
// Find the index position of the final digit in the string (in this case '4')
var postcodeIndex = postCode.indexOf(postCode.match(/\d(?=\D*$)/g));
// Slice the final postcode at the index point, add a space and join back together.
var finalPostcode = [postCode.slice(0, postcodeIndex), ' ', postCode.slice(postcodeIndex)].join('');
return finalPostcode;
I am getting the following results when I change the set postcost:
CB30QB becomes CB3 0QB - Correct
N12NL becomes N1 2NL - Correct
CB249LQ becomes CB24 9LQ - Correct
OX144FB becomes OX1 44FB - Incorrect
OX145FB becomes OX14 5FB - Correct
It seems that the issue might be to do with having two digits of the same value as most other combinations seem to work.
Does anyone know how I can fix this?
I should use string.replace
string.replace(/^(.*)(\d)/, "$1 $2");
DEMO
You can use replace() with regex, you need to place space before 3 letters from the end
document.write('CB30QB'.replace(/^(.*)(.{3})$/,'$1 $2')+'<br>');
document.write('N12NL'.replace(/^(.*)(.{3})$/,'$1 $2')+'<br>');
document.write('CB249LQ'.replace(/^(.*)(.{3})$/,'$1 $2')+'<br>');
document.write('OX144FB'.replace(/^(.*)(.{3})$/,'$1 $2'));
As everyone else is answering, .replace() is easier. However, let me point what's wrong in the code.
The problem is you're using postCode.indexOf() to find the first occurence of what has been matched. In this case:
Text: OX144FB
Match: ^ match is correct: "4"
Text: OX144FB
IndexOf: ^ first occurence of "4"
To fix it, use the .index of the match object:
// Find the index position of the final digit in the string (in this case '4')
var postcodeIndex = postCode.match(/\d(?=\D*$)/g).index;
var postCode = "OX144FB";
return postCode.replace(/^(.*)(\d)(.*)/, "$1 $2$3");
Using the String.prototype.replace method is obviously the easiest way:
return postCode.replace(/(?=\d\D*$)/, ' ');
or using the greediness:
return postCode.replace(/^(.*)(?=\d)/, '$1 ');
Your previous code doesn't work because you are searching with indexOf the substring matched with the String.prototype.match() method (that is the last digit before the end). But if this digit is several times in the string, indexOf will return the position of the first occurrence.
As an aside, when you want to find the position of a match in a string, use the String.prototype.search() method that returns this position.
This is an old problem, but whilst Avinash Raj's solution works, it only works if all your postcodes are without spaces. If you have a mix, and you want to regularize them to having a single space, you can use this regex:
string.replace(/(\S*)\s*(\d)/, "$1 $2");
DEMO - it even works with more than one space!

How to remove the last word in a string using JavaScript

How can I remove the last word in the string using JavaScript?
For example, the string is "I want to remove the last word."
After using removal, the string in the textbox will display "I want to remove the last"
I've seen how to remove the last character using the substring function, but because the last word can be different every time. Is there a way to count how many words are required to remove in JavaScript?
Use:
var str = "I want to remove the last word.";
var lastIndex = str.lastIndexOf(" ");
str = str.substring(0, lastIndex);
Get the last space and then get the substring.
An easy way to do that would be to use JavaScript's lastIndexOf() and substr() methods:
var myString = "I want to remove the last word";
myString = myString.substring(0, myString.lastIndexOf(" "));
You can do a simple regular expression like so:
"I want to remove the last word.".replace(/\w+[.!?]?$/, '')
>>> "I want to remove the last"
Finding the last index for " " is probably faster though. This is just less code.
Following answer by Amir Raminfar, I found this solution. In my opinion, it's better than accepted answer, because it works even if you have a space at the end of the string or with languages (like French) that have spaces between last word and punctuation mark.
"Je veux supprimer le dernier mot !".replace(/[\W]*\S+[\W]*$/, '')
"Je veux supprimer le dernier"
It strips also the space(s) and punctuation marks before the last word, as the OP implicitly required.
Peace.
Fooling around just for fun, this is a funny and outrageous way to do it!
"I want to remove the last word.".split(" ").reverse().slice(1).reverse().join(" ")
Use the split function:
var myString = "I want to remove the last word";
var mySplitResult = myString.split(" ");
var lastWord = mySplitResult[mySplitResult.length-1]
The shortest answer to this question would be as below,
var str="I want to remove the last word".split(' ');
var lastword=str.pop();
console.log(str.join(' '));
You can match the last word following a space that has no word characters following it.
word=/s+\W*([a-zA-Z']+)\W*$/.exec(string);
if(word) alert(word[1])
If anyone else here is trying to split a string name in to last name and first name, please make sure to handle the case in which the name has only word.
let recipientName = _.get(response, 'shipping_address.recipient_name');
let lastWordIndex = recipientName.lastIndexOf(" ");
let firstName = (lastWordIndex == -1) ? recipientName : recipientName.substring(0, lastWordIndex);
let lastName = (lastWordIndex == -1) ? '' : recipientName.substring(lastWordIndex + 1);
To get the last word
const animals = "I want to remove the last word.".split(" ");
console.log(animals.slice(-1));
Expected output: word.
To remove the last word
console.log(animals.slice(0, -1).join(" ");
Expected output: "I want to remove the last"

Replace multiple whitespaces with single whitespace in JavaScript string

I have strings with extra whitespace characters. Each time there's more than one whitespace, I'd like it be only one. How can I do this using JavaScript?
Something like this:
var s = " a b c ";
console.log(
s.replace(/\s+/g, ' ')
)
You can augment String to implement these behaviors as methods, as in:
String.prototype.killWhiteSpace = function() {
return this.replace(/\s/g, '');
};
String.prototype.reduceWhiteSpace = function() {
return this.replace(/\s+/g, ' ');
};
This now enables you to use the following elegant forms to produce the strings you want:
"Get rid of my whitespaces.".killWhiteSpace();
"Get rid of my extra whitespaces".reduceWhiteSpace();
Here's a non-regex solution (just for fun):
var s = ' a b word word. word, wordword word ';
// with ES5:
s = s.split(' ').filter(function(n){ return n != '' }).join(' ');
console.log(s); // "a b word word. word, wordword word"
// or ES2015:
s = s.split(' ').filter(n => n).join(' ');
console.log(s); // "a b word word. word, wordword word"
Can even substitute filter(n => n) with .filter(String)
It splits the string by whitespaces, remove them all empty array items from the array (the ones which were more than a single space), and joins all the words again into a string, with a single whitespace in between them.
using a regular expression with the replace function does the trick:
string.replace(/\s/g, "")
I presume you're looking to strip spaces from the beginning and/or end of the string (rather than removing all spaces?
If that's the case, you'll need a regex like this:
mystring = mystring.replace(/(^\s+|\s+$)/g,' ');
This will remove all spaces from the beginning or end of the string. If you only want to trim spaces from the end, then the regex would look like this instead:
mystring = mystring.replace(/\s+$/g,' ');
Hope that helps.
jQuery.trim() works well.
http://api.jquery.com/jQuery.trim/
I know I should not necromancy on a subject, but given the details of the question, I usually expand it to mean:
I want to replace multiple occurences of whitespace inside the string with a single space
...and... I do not want whitespaces in the beginnin or end of the string (trim)
For this, I use code like this (the parenthesis on the first regexp are there just in order to make the code a bit more readable ... regexps can be a pain unless you are familiar with them):
s = s.replace(/^(\s*)|(\s*)$/g, '').replace(/\s+/g, ' ');
The reason this works is that the methods on String-object return a string object on which you can invoke another method (just like jQuery & some other libraries). Much more compact way to code if you want to execute multiple methods on a single object in succession.
var x = " Test Test Test ".split(" ").join("");
alert(x);
Try this.
var string = " string 1";
string = string.trim().replace(/\s+/g, ' ');
the result will be
string 1
What happened here is that it will trim the outside spaces first using trim() then trim the inside spaces using .replace(/\s+/g, ' ').
How about this one?
"my test string \t\t with crazy stuff is cool ".replace(/\s{2,9999}|\t/g, ' ')
outputs "my test string with crazy stuff is cool "
This one gets rid of any tabs as well
If you want to restrict user to give blank space in the name just create a if statement and give the condition. like I did:
$j('#fragment_key').bind({
keypress: function(e){
var key = e.keyCode;
var character = String.fromCharCode(key);
if(character.match( /[' ']/)) {
alert("Blank space is not allowed in the Name");
return false;
}
}
});
create a JQuery function .
this is key press event.
Initialize a variable.
Give condition to match the character
show a alert message for your matched condition.

Searching for a last word in JavaScript

I am doing some logic for the last word that is on the sentence. Words are separated by either space or with a '-' character.
What is easiest way to get it?
Edit
I could do it by traversing backwards from the end of the sentence, but I would like to find better way
Try splitting on a regex that matches spaces or hyphens and taking the last element:
var lastWord = function(o) {
return (""+o).replace(/[\s-]+$/,'').split(/[\s-]/).pop();
};
lastWord('This is a test.'); // => 'test.'
lastWord('Here is something to-do.'); // => 'do.'
As #alex points out, it's worth trimming any trailing whitespace or hyphens. Ensuring the argument is a string is a good idea too.
Using a regex:
/.*[\s-](\S+)/.exec(str)[1];
that also ignores white-space at the end
Have you tried the lastIndexOf function http://www.w3schools.com/jsref/jsref_lastIndexOf.asp
Or Split function http://www.w3schools.com/jsref/jsref_split.asp
Here is a similar discussion have a look
You can try something like this...
<script type="text/javascript">
var txt = "This is the sample sentence";
spl = txt.split(" ");
for(i = 0; i < spl.length; i++){
document.write("<br /> Element " + i + " = " + spl[i]);
}
</script>
Well, using Split Function
string lastWord = input.Split(' ').Last();
or
string[] parts = input.Split(' ');
string lastWord = parts[parts.Length - 1];
While this would work for this string, it might not work for a slightly different string, so either you'll have to figure out how to change the code accordingly, or post all the rules.
string input = ".... ,API";
here, the comma would be part of the "word".
Also, if the first method of obtaining the word is correct, ie. everything after the last space, and your string adheres to the following rules:
Will always contain at least one space
Does not end with one or more space (in case of this you can trim it)
then you can use this code that will allocate fewer objects on the heap for GC to worry about later:
string lastWord = input.Substring(input.LastIndexOf(' ') + 1);
I hope its help

remove unwanted commas in JavaScript

I want to remove all unnecessary commas from the start/end of the string.
eg; google, yahoo,, , should become google, yahoo.
If possible ,google,, , yahoo,, , should become google,yahoo.
I've tried the below code as a starting point, but it seems to be not working as desired.
trimCommas = function(s) {
s = s.replace(/,*$/, "");
s = s.replace(/^\,*/, "");
return s;
}
In your example you also want to trim the commas if there's spaces between them at the start or at the end, use something like this:
str.replace(/^[,\s]+|[,\s]+$/g, '').replace(/,[,\s]*,/g, ',');
Note the use of the 'g' modifier for global replace.
You need this:
s = s.replace(/[,\s]{2,}/,""); //Removes double or more commas / spaces
s = s.replace(/^,*/,""); //Removes all commas from the beginning
s = s.replace(/,*$/,""); //Removes all commas from the end
EDIT: Made all the changes - should work now.
My take:
var cleanStr = str.replace(/^[\s,]+/,"")
.replace(/[\s,]+$/,"")
.replace(/\s*,+\s*(,+\s*)*/g,",")
This one will work with opera, internet explorer, whatever
Actually tested this last one, and it works!
What you need to do is replace all groups of "space and comma" with a single comma and then remove commas from the start and end:
trimCommas = function(str) {
str = str.replace(/[,\s]*,[,\s]*/g, ",");
str = str.replace(/^,/, "");
str = str.replace(/,$/, "");
return str;
}
The first one replaces every sequence of white space and commas with a single comma, provided there's at least one comma in there. This handles the edge case left in the comments for "Internet Explorer".
The second and third get rid of the comma at the start and end of string where necessary.
You can also add (to the end):
str = str.replace(/[\s]+/, " ");
to collapse multi-spaces down to one space and
str = str.replace(/,/g, ", ");
if you want them to be formatted nicely (space after each comma).
A more generalized solution would be to pass parameters to indicate behaviour:
Passing true for collapse will collapse the spaces within a section (a section being defined as the characters between commas).
Passing true for addSpace will use ", " to separate sections rather than just "," on its own.
That code follows. It may not be necessary for your particular case but it might be better for others in terms of code re-use.
trimCommas = function(str,collapse,addspace) {
str = str.replace(/[,\s]*,[,\s]*/g, ",").replace(/^,/, "").replace(/,$/, "");
if (collapse) {
str = str.replace(/[\s]+/, " ");
}
if (addspace) {
str = str.replace(/,/g, ", ");
}
return str;
}
First ping on Google for "Javascript Trim": http://www.somacon.com/p355.php. You seem to have implemented this using commas, and I don't see why it would be a problem (though you escaped in the second one and not in the first).
Not quite as sophisticated, but simple with:
',google,, , yahoo,, ,'.replace(/\s/g, '').replace(/,+/g, ',');
You should be able to use only one replace call:
/^( *, *)+|(, *(?=,|$))+/g
Test:
'google, yahoo,, ,'.replace(/^( *, *)+|(, *(?=,|$))+/g, '');
"google, yahoo"
',google,, , yahoo,, ,'.replace(/^( *, *)+|(, *(?=,|$))+/g, '');
"google, yahoo"
Breakdown:
/
^( *, *)+ # Match start of string followed by zero or more spaces
# followed by , followed by zero or more spaces.
# Repeat one or more times
| # regex or
(, *(?=,|$))+ # Match , followed by zero or more spaces which have a comma
# after it or EOL. Repeat one or more times
/g # `g` modifier will run on until there is no more matches
(?=...) is a look ahead will will not move the position of the match but only verify that a the characters are after the match. In our case we look for , or EOL
match() is much better tool for this than replace()
str = " aa, bb,, cc , dd,,,";
newStr = str.match(/[^\s,]+/g).join(",")
alert("[" + newStr + "]")
When you want to replace ",," ",,,", ",,,," and ",,,,," below code will be removed by ",".
var abc = new String("46590,26.91667,75.81667,,,45346,27.18333,78.01667,,,45630,12.97194,77.59369,,,47413,19.07283,72.88261,,,45981,13.08784,80.27847,,");
var pqr= abc.replace(/,,/g,',').replace(/,,/g, ',');
alert(pqr);

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