Alternate adding a character to the beginning and end of string - javascript

I am trying to solve a Javascript puzzle. I need to write a function that uses a while loop to add a character to the beginning of string and then on the next loop adds the character to the end of the string and to the beginning on the loop after that. The function takes two parameters a string and a number of characters to add.
So far I have
function padIt(str,n){
//coding here
var newStr = "";
var padding = "*";
var i = 0;
while(i<=n){
if (i%2===0){
newStr = newStr+padding;
} else{
newStr = padding+str;
}
i++;
}
return newStr;
}
I am passing the first two test cases but it won't work properly for the third time through the loop. Expecting "* * a *" for n = 3 but only getting "*a". It has to be a while loop so I don't know if I am not setting the loop up correctly or if I am messing up the variables. Any help is greatly appreciated as I am totally lost.

You can do it by writing code like below,
function padIt(str,n, pad = "*"){
var left = Math.ceil(n/2), right = n - left;
return pad.repeat(left) + str + pad.repeat(right);
}
And this function would print,
console.log("a", 1); // "*a"
console.log("a", 2); // "*a*"
console.log("a", 10); // "*****a*****"
Thing need to be read after implementing this code,
String.prototype.repeat()

You need to comment your newStr+=padding; line.
Here is the refined code,
function padIt(str,n){
//coding here
var newStr = "";
var padding = "*";
var i = 0;
while(i<=n){
i++;
newStr=padding+str;
//newStr+=padding;
}
return newStr;
}
HTH

function padIt(str,n){
while(n>0){
if(n%2 === 0){
str = str + '*';
} else{
str = '*' + str;
}
n--;
}
return str;
}

Related

Splitting a string into multiple lines in javascript

I'm trying to find a way to split long strings to multiple lines so what I'm doing is insert text into an image and if it gets too long it overflows, newlines work but it wouldn't be best idea to let user add the newlines and split it in code, so if i give it a limit it checks if its over limit split to two lines or i mean a newline \n between it, however that's easy but my problem is when it comes that the second part is also over the limit then it should split it in to 3 newlines, how would you go implement that?
Examples
split("sometext", 5); // somet\next
split("Hello", 2); // he\nll\no
Very straightforward answer to your question:
function customSplit(str, maxLength){
if(str.length <= maxLength)
return str;
var reg = new RegExp(".{1," + maxLength + "}","g");
var parts = str.match(reg);
return parts.join('\n');
}
You need a function like the following:
function split(str, maxWidth) {
const newLineStr = "\n";
done = false;
res = '';
do {
found = false;
// Inserts new line at first whitespace of the line
for (i = maxWidth - 1; i >= 0; i--) {
if (testWhite(str.charAt(i))) {
res = res + [str.slice(0, i), newLineStr].join('');
str = str.slice(i + 1);
found = true;
break;
}
}
// Inserts new line at maxWidth position, the word is too long to wrap
if (!found) {
res += [str.slice(0, maxWidth), newLineStr].join('');
str = str.slice(maxWidth);
}
if (str.length < maxWidth)
done = true;
} while (!done);
return res + str;
}
function testWhite(x) {
const white = new RegExp(/^\s$/);
return white.test(x.charAt(0));
};
console.log(split("sometext", 5));
console.log(split("Hello", 2));
https://j11y.io/snippets/wordwrap-for-javascript/
Wraps using specified limit on characters. :)
What kind of interface are you building? If it's a web interface, you should style the string on the front end, instead of modifying it on the data layer.
If it's a text based interface and you really need to do this, then you can get the first n characters while there is a non-empty string, then join with '\n'. Assuming you have underscore:
function split(str, n) {
let numberOfSegments = Math.ceil(_.size(str) / n);
let segments = _.map(_.range(numberOfSegments),
segmentIndex => str.substr(segmentIndex * n, n));
return segments.join('\n');
}

Removing duplicate spaces from input

<textarea id="check" cols="50" rows="20"></textarea>
<script>
var text = document.getElementById("check").value;
var lengthA = text;
for (var i = 0; i < lengthA.length; i++) {
var space = " ";
if (lengthA[i] === space) {
var next = lengthA[i] + 1;
if (next === space) {
lengthA.replace(lengthA[i], "");
}
}
}
var length3 = lengthA.length - length2;
var words = length3 + 1;
</script>
Alright bois, me got a problemo! Im attempting to make a word counter through the law that each space equals a word (1:1). Im not sure why it is not working, it makes sense to me in my mind. I have attempted several alternatives and dwelled hours upon trying to fix this chunk. Thank you in advance to anyone that answers, even if it doesn't work! :)
EDIT: Regular expressions did the trick and replaced the incorrectly used for loop and if statements. Thanks
How about just the below -
var text = document.getElementById("check").value.replace (/ +/g, " ");
Not sure, why you would need a for loop to begin with.
/ +/ will more than 1 space
g will do all the changes throughout the text
To remove the duplicate space, the following code
lengthA.replace(lengthA[i], "");
should be
lengthA = lengthA.substring(0, i) + lengthA.substring(i + 1);
// i should not increase
i--;
continue;
You misunderstand the usage of replace.
Use str.replace() of JavaScript to do this. This will remove not only space but also work for tabs, newlines etc.
Usage:
var string = string.replace(/\s\s+/g, ' ');
So change below code:
var lengthA = text;
for (var i = 0; i < lengthA.length; i++) {
var space = " ";
if (lengthA[i] === space) {
var next = lengthA[i] + 1;
if (next === space) {
lengthA.replace(lengthA[i], "");
}
}
}
To this:
var lengthA = text.replace(/\s\s+/g, ' ');
Reference here : https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/replace

How can I exclude punctuation in "pig latin" function?

I apologize if this question has been answered somewhere - please point me in the right direction if so. I have read through a bunch of solutions and have not yet cracked it!
Sooo...basically, I need to:
Move the first letter of each word to the end of it, then add "ay" to the end of the word. Leave punctuation marks untouched.
This is my code so far:
function pigIt(str) {
var newStr = str.split(" ");
var changed = newStr.map(function(input) {
return input.substring(1) + input.charAt(0) + "ay";
});
changed = changed.join(" ");
return changed;
}
console.log(pigIt('Pig latin is cool'));
As you can see, the code will work for any input that doesn't include punctuation. Great. Now I need to maybe add a Regex somewhere to exclude punctuation but I don't know where to put it! Please help!!
You could split by the word boundary /(\W+)/ while capturing separator. Transform words only. And then join back.
function pigIt(str) {
var newStr = str.split(/(\W+)/); // ['Pig', ' ', 'latin', ',- ',..]
var changed = newStr.map(function(input) {
if (!/\w/.test(input)) return input // keep non word elements as is
return input.substring(1) + input.charAt(0) + "ay";
});
return changed.join("");
}
console.log(pigIt('Pig latin,- is cool!'));
I think because you are going to want to put the punctuation back in the same place after processing, then you will probably be better of doing it all manually.
Loop the input 1 char at a time and build a 'word buffer', every time you hit a non-letter character then process the word buffer and append the non-letter character too.
function pigIt(str) {
var process = function(s) {
if (s.length < 2) {
return s;
}
return s.substring(1) + s.charAt(0) + "ay";
};
var result = '';
var buffer = '';
for (var i = 0; i < str.length; i++) {
var c = str[i];
if (c.match(/[a-zA-Z]/i)) {
buffer += c;
} else {
if (buffer.length) {
result += process(buffer);
buffer = '';
}
result += c;
}
}
result += process(buffer);
buffer = '';
return result;
}
var output = pigIt('Pig latin is cool.');
console.log(output);

I don't know how to fix my reverse array/string

so I need to be able to enter a string and have it reversed. I must have one library JS file and one regular JS file. Here is my library JS file:
function reverseString(string) {
var reversedString= "";
for(var i = string.length -; i >=; --i) {
reversedString = reversedString + string[i];
}
return reversedString;
}
and here is my regular one
var stringEntered = prompt("Enter a string:")
var newString = reverseString(stringEntered);
document.write("the reverse of the string \" + stringEntered + \ " is \" + newString + ".")
I entered it the exact same way my professor showed us, and I when I try to run my HTML file (which is coded to call both these files), nothing happens. What am I missing?
There're a lot of syntax issues. Here's a working code:
function reverseString(string) {
var reversedString = "";
// This loop had a lot of basic syntax issues and also
// "i" was starting from the length value, while a string
// is a character array and array indexes start from 0 instead of 1
for (var i = string.length - 1; i >= 0; --i) {
reversedString = reversedString + string[i];
}
return reversedString;
}
var stringEntered = prompt("Enter a string:");
var newString = reverseString(stringEntered);
// Here I found a mess of "/" characters
// I've changed the horrible document.write with alert so you can check the result without opening the debugger...
alert("the reverse of the string " + stringEntered + " is " + newString + ".")
Here is a concise method of reversing a string:
function reverseString(string) {
return string.split('').reverse().join('');
}
var str = prompt("Enter a string", "a racecar dad");
alert(reverseString(str));
Turn it into an array, reverse the array, turn it back into a string.
Edit: Sorry, didn't see #SidneyLiebrand's comment telling you to do the same.

Javascript word-count for any given DOM element

I'm wondering if there's a way to count the words inside a div for example. Say we have a div like so:
<div id="content">
hello how are you?
</div>
Then have the JS function return an integer of 4.
Is this possible? I have done this with form elements but can't seem to do it for non-form ones.
Any ideas?
g
If you know that the DIV is only going to have text in it, you can KISS:
var count = document.getElementById('content').innerHTML.split(' ').length;
If the div can have HTML tags in it, you're going to have to traverse its children looking for text nodes:
function get_text(el) {
ret = "";
var length = el.childNodes.length;
for(var i = 0; i < length; i++) {
var node = el.childNodes[i];
if(node.nodeType != 8) {
ret += node.nodeType != 1 ? node.nodeValue : get_text(node);
}
}
return ret;
}
var words = get_text(document.getElementById('content'));
var count = words.split(' ').length;
This is the same logic that the jQuery library uses to achieve the effect of its text() function. jQuery is a pretty awesome library that in this case is not necessary. However, if you find yourself doing a lot of DOM manipulation or AJAX then you might want to check it out.
EDIT:
As noted by Gumbo in the comments, the way we are splitting the strings above would count two consecutive spaces as a word. If you expect that sort of thing (and even if you don't) it's probably best to avoid it by splitting on a regular expression instead of on a simple space character. Keeping that in mind, instead of doing the above split, you should do something like this:
var count = words.split(/\s+/).length;
The only difference being on what we're passing to the split function.
Paolo Bergantino's second solution is incorrect for empty strings or strings that begin or end with whitespaces. Here's the fix:
var count = !s ? 0 : (s.split(/^\s+$/).length === 2 ? 0 : 2 +
s.split(/\s+/).length - s.split(/^\s+/).length - s.split(/\s+$/).length);
Explanation: If the string is empty, there are zero words; If the string has only whitespaces, there are zero words; Else, count the number of whitespace groups without the ones from the beginning and the end of the string.
string_var.match(/[^\s]+/g).length
seems like it's a better method than
string_var.split(/\s+/).length
At least it won't count "word " as 2 words -- ['word'] rather than ['word', '']. And it doesn't really require any funny add-on logic.
Or just use Countable.js to do the hard job ;)
document.deepText= function(hoo){
var A= [];
if(hoo){
hoo= hoo.firstChild;
while(hoo!= null){
if(hoo.nodeType== 3){
A[A.length]= hoo.data;
}
else A= A.concat(arguments.callee(hoo));
hoo= hoo.nextSibling;
}
}
return A;
}
I'd be fairly strict about what a word is-
function countwords(hoo){
var text= document.deepText(hoo).join(' ');
return text.match(/[A-Za-z\'\-]+/g).length;
}
alert(countwords(document.body))
Or you can do this:
function CountWords (this_field, show_word_count, show_char_count) {
if (show_word_count == null) {
show_word_count = true;
}
if (show_char_count == null) {
show_char_count = false;
}
var char_count = this_field.value.length;
var fullStr = this_field.value + " ";
var initial_whitespace_rExp = /^[^A-Za-z0-9]+/gi;
var left_trimmedStr = fullStr.replace(initial_whitespace_rExp, "");
var non_alphanumerics_rExp = rExp = /[^A-Za-z0-9]+/gi;
var cleanedStr = left_trimmedStr.replace(non_alphanumerics_rExp, " ");
var splitString = cleanedStr.split(" ");
var word_count = splitString.length -1;
if (fullStr.length <2) {
word_count = 0;
}
if (word_count == 1) {
wordOrWords = " word";
} else {
wordOrWords = " words";
}
if (char_count == 1) {
charOrChars = " character";
} else {
charOrChars = " characters";
}
if (show_word_count & show_char_count) {
alert ("Word Count:\n" + " " + word_count + wordOrWords + "\n" + " " + char_count + charOrChars);
} else {
if (show_word_count) {
alert ("Word Count: " + word_count + wordOrWords);
} else {
if (show_char_count) {
alert ("Character Count: " + char_count + charOrChars);
}
}
}
return word_count;
}
The get_text function in Paolo Bergantino's answer didn't work properly for me when two child nodes have no space between them. eg <h1>heading</h1><p>paragraph</p> would be returned as headingparagraph (notice lack of space between the words). So prepending a space to the nodeValue fixes this. But it introduces a space at the front of the text but I found a word count function that trims it off (plus it uses several regexps to ensure it counts words only). Word count and edited get_text functions below:
function get_text(el) {
ret = "";
var length = el.childNodes.length;
for(var i = 0; i < length; i++) {
var node = el.childNodes[i];
if(node.nodeType != 8) {
ret += node.nodeType != 1 ? ' '+node.nodeValue : get_text(node);
}
}
return ret;
}
function wordCount(fullStr) {
if (fullStr.length == 0) {
return 0;
} else {
fullStr = fullStr.replace(/\r+/g, " ");
fullStr = fullStr.replace(/\n+/g, " ");
fullStr = fullStr.replace(/[^A-Za-z0-9 ]+/gi, "");
fullStr = fullStr.replace(/^\s+/, "");
fullStr = fullStr.replace(/\s+$/, "");
fullStr = fullStr.replace(/\s+/gi, " ");
var splitString = fullStr.split(" ");
return splitString.length;
}
}
EDIT
kennebec's word counter is really good. But the one I've found includes a number as a word which is what I needed. Still, that's easy to add to kennebec's. But kennebec's text retrieval function will have the same problem.
This should account for preceding & trailing whitespaces
const wordCount = document.querySelector('#content').innerText.trim().split(/\s+/).length;
string_var.match(/[^\s]+/g).length - 1;

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