Without using the split reverse and join functions, how would one do such a thing?
The Problem Given: Reverse the words in a string
Sample Input: "Hello World"
Sample Output: "World Hello"
<script>
var newString = "";
var theString = prompt("Enter a Phrase that you would like to reverse (Ex. Hello world)");
newString = theString.split(" ").reverse().join(" ")
document.write(newString);
</script>
Arrays can be used like stacks out of the box. And stacks are LIFO, which is what you need.
function reverseWords(str) {
var word, words, reverse;
words = str.match(/(?:\w+)/g);
reverse = '';
while(word = words.pop()) {
reverse += word + ' ';
}
return reverse.trim();
}
reverseWords('hello world');
Or use the call stack as your stack:
function reverseWords(str) {
var result = '';
(function readWord(i = 0) {
var word = '';
if(i > str.length) {
return '';
}
while(str[i] !== ' ' && i < str.length) {
word += str[i];
i++;
}
readWord(++i); // Skip over delimiter.
result += word + ' ';
}());
return result.trim();
}
reverseWords('hello world');
Another idea for reversing the words in a String is using a Stack data structure. Like so:
var newString = "";
var theString = prompt("Enter a Phrase that you would like to reverse (Ex. Hello world)");
var word = "";
var c;
var stack = [];
for (var i = 0, len = theString.length; i < len; i++) {
c = theString[i];
word += c;
if (c == " " || i == (len-1)) {
word = word.trim();
stack.push(word);
word = "";
}
}
while (s = stack.pop()) {
newString += s + " ";
}
console.log(newString);
You could also go fancy and try something like this:
I couldn't come up with a shorter solution.
var newString = "";
var theString = prompt("Enter a Phrase that you would like to reverse (Ex. Hello world)");
theString.replace(/[^\s]*/g, function (value) {
newString = value + ' ' + newString;
});
document.write(newString);
Of the millions of different solutions, the least amount of typing I could come up with involves using lastIndexOf and substring.
var str = "The quick brown fox",
reversed = "",
idx;
while(true) {
idx = str.lastIndexOf(" ")
reversed = reversed + str.substring(idx).trim() + " "
if (idx < 0) break;
str = str.substring(0, idx)
}
reversed.trim() # Oh, yes, trim too
Output:
"fox brown quick The"
The simplest way to do in javascript. Here replace() have /,/g it will replace all comma from the string to space.
var msg = 'Hello world I am Programmer';
var newstr = msg.split(" ").reverse().join().replace(/,/g, ' ');
console.log(newstr)
;
Related
Having trouble coming up with code doing this.
So for example here is my string.
var str = "Hello how are you today?";
How would I manipulate this string to return the position of the first letter of each word using a loop?
this will give you the result with less complicated code and a single loop
function foo(str) {
var pos = [];
var words = str.split(' ');
pos.push(1);
var prevWordPos;
for (var i = 1; i < words.length; i++) {
prevWordPos = pos[i - 1] + words[i - 1].length;
pos.push((str.indexOf(words[i], prevWordPos) + 1));
}
return pos;
}
You should search for a question before asking it in case it's already been asked and answered.
Get first letter of each word in a string, in Javascript
You can use a regexp replace passing a function instead of a replacement string, this will call the function for each match:
str.replace(/[^ ]+/g, function(match, pos) {
console.log("Word " + match + " starts at position " + pos);
});
The regexp meaning is:
[^ ]: anything excluding space
+: one or more times
"g" option: not only first match, but each of them
in other words the function will be called with sequences of non-spaces. Of course you can define what you consider a "word" differently.
Here is a Solution with two Loops, i hope that is close enough ;)
var starts = [];
var str = "How are you doing today?";
//var count = 0;
var orgStr = str;
while (str.indexOf(" ") > 0) {
if (starts.length > 0) {
starts.push(starts[starts.length - 1] + str.indexOf(" ") +1);
} else {
starts.push(1);
starts.push(str.indexOf(" ") +2);
//alert(str);
}
str = str.substring(str.indexOf(" ") + 1);
}
for (var i = 0; i < starts.length; i++) {
alert(starts[i] + ": " + orgStr.substring(starts[i]-1,starts[i]))
}
Easiest would be to search a regular expression \b\w and collect match.start() match.index for each match. Loop while there's matches.
EDIT: wrong language. lol.
I am writing a function to make slug from input.
var vslug = function (str) {
str = str.replace(/^\s+|\s+$/g, '');
str = str.toLowerCase();
var vregex = /(?:\.([^.]+))?$/;
var filename = str.replace(vregex.exec(str)[0],'');
var extension = vregex.exec(str)[1];
var from = "àáäâèéëêìíïîıòóöôùúüûñçşğ·/,:;";
var to = "aaaaeeeeiiiiioooouuuuncsg_____";
for (var i = 0; i < from.length; i++) {
console.log('before ' + str);
str = filename.replace(new RegExp(from[i], 'g'), to[i]);
console.log('after ' + str);
}
str = str.replace(/[^a-z0-9 _-]/g, '')
.replace(/\s+/g, '_')
.replace(/-+/g, '_');
if (typeof extension !== "undefined") {
return str+'.'+extension;
} else {
return str;
}
};
I can't make this part - I gone blind. Any help is appreciated..
var from = "àáäâèéëêìíïîıòóöôùúüûñçşğ·/,:;";
var to = "aaaaeeeeiiiiioooouuuuncsg_____";
for (var i = 0; i < from.length; i++) {
console.log('before ' + str);
str = filename.replace(new RegExp(from[i], 'g'), to[i]);
console.log('after ' + str);
}
filename is not changed - the variable names the same string, and the string cannot be modified. As such, each loop starts working on the original string again when it uses filename.replace...
Instead, eliminate filename (or integrate it fully) and use str = str.replace..
str = str.replace(vregex.exec(str)[0],'');
for (var i = 0; i < from.length; i++) {
str = str.replace(new RegExp(from[i], 'g'), to[i]);
// ^-- next loop gets new value
}
(Also, this could be handled with a replacement function and a map instead of n-loops and there might be a Unicode library for JavaScript available..)
An approach using a map and a replacement function might look like:
// Specify map somewhere reusable; can be built from paired arrays for simplicity.
var replacements = {"à":"a", "á":"a", .. ";":"_"}
// Object.keys is ES5, shim as needed. e.g. result: [à;á..]
var alternation = "[" + Object.keys(replacements).join("") + "]"
// This regex will match all characters we are trying to match.
var regex = new Regex(alternation, "g")
str = str.replace(regex, function (m) {
var r = replacements[m]
return r || m
})
See String.replace(regex, function)
function LetterChanges(str) {
var alphabet = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
for (var i = 0; i < str.length; i++) {
var index = alphabet.indexOf(str[i])
if (/[a-zA-Z]/.test(str[i])) {
str = str.replace(str[i], alphabet.charAt(index + 1));
}
if (/[aeiou]/.test(str[i])) {
str = str.replace(str[i], alphabet.charAt(index + 26));
}
}
return str;
}
When I call LetterChanges("hello"), it returns 'Ifmmp' which is correct, but when "sent" is passed it returns 'ufOt' instead of 'tfOu'. Why is that?
str.replace() replaces the first occurrence of the match in the string with the replacement. LetterChanges("sent") does the following:
i = 0 : str.replace("s", "t"), now str = "tent"
i = 1 : str.replace("e", "f"), now str = "tfnt"
i = 2 : str.replace("n", "o"), now str = "tfot", then
str.replace("o", "O"), now str = "tfOt"
i = 3 : str.replace("t", "u"), now str = "ufOt"
return str
There are several issues. The main one is that you could inadvertently change the same letter several times.
Let's see what happens to the s in sent. You first change it to t. However, when it comes to changing the final letter, which is also t, you change the first letter again, this time from t to u.
Another, smaller, issue is the handling of the letter z.
Finally, your indexing in the second if is off by one: d becomes D and not E.
You can use String.replace to avoid that:
function LetterChanges(str) {
return str.replace(/[a-zA-Z]/g, function(c){
return String.fromCharCode(c.charCodeAt(0)+1);
}).replace(/[aeiou]/g, function(c){
return c.toUpperCase();
});
}
But there is still a bug: LetterChanges('Zebra') will return '[fcsb'. I assume that is not your intention. You will have to handle the shift.
Try this one:
function LetterChanges(str) {
var alphabet = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
var result = '';
var temp;
for (var i = 0; i < str.length; i++) {
var index = alphabet.indexOf(str[i])
if (/[a-zA-Z]/.test(str[i])) {
//str = str.replace(str[i], alphabet.charAt(index + 1));
temp= alphabet.charAt(index + 1);
index = index+1;
}
else if(str[i] == ' '){
temp = ' ';
}
if (/[aeiou]/.test(temp)) {
temp = alphabet.charAt(index + 26);
}
result += temp;
}
return result;
}
var str = 'bcd12';
str = str.replace(/[a-z]/gi, function(char) { //call replace method
char = String.fromCharCode(char.charCodeAt(0)+1);//increment ascii code of char variable by 1 .FromCharCode() method will convert Unicode values into character
if (char=='{' || char=='[') char = 'a'; //if char values goes to "[" or"{" on incrementing by one as "[ ascii value is 91 just after Z" and "{ ascii value is 123 just after "z" so assign "a" to char variable..
if (/[aeiuo]/.test(char)) char = char.toUpperCase();//convert vowels to uppercase
return char;
});
console.log(str);
Check this code sample. There is no bug in it. Not pretty straight forward but Works like a charm. Cheers!
function LetterChanges(str) {
var temp = str;
var tempArr = temp.split("");//Split the input to convert it to an Array
tempArr.forEach(changeLetter);/*Not many use this but this is the referred way of using loops in javascript*/
str = tempArr.join("");
// code goes here
return str;
}
function changeLetter(ele,index,arr) {
var lowerLetters ="abcdefghijklmnopqrstuvwxyza";
var upperLetters ="ABCDEFGHIJKLMNOPQRSTUVWXYZA";
var lowLetterArr = lowerLetters.split("");
var upLetterArr = upperLetters.split("");
var i =0;
for(i;i<lowLetterArr.length;i++){
if(arr[index] === lowLetterArr[i]){
arr[index] = lowLetterArr[i+1];
arr[index]=arr[index].replace(/[aeiou]/g,arr[index].toUpperCase());
return false;
}
if(arr[index] === upLetterArr[i]){
arr[index] = upLetterArr[i+1];
arr[index]=arr[index].replace(/[aeiou]/g,arr[index].toUpperCase());
return false;
}
}
}
// keep this function call here
// to see how to enter arguments in JavaScript scroll down
LetterChanges(readline());
What I need to do is make this function to where it splits each part of the string entered, and then puts pig latin on each word, meaning it adds ay at the end of each word. Here's what I have so far:
function pigLatin(whatWeTitle) {
var alertThis = " ";
var splitArray = whatWeTitle.split(" ");
for ( i = 0; i < splitArray.length; i++) {
alertThis = makeSentenceCase(splitArray[i]) + " ";
var newWord3 = splitArray.substring(1, whatWeTitle.length) + newWord + 'ay';
alert(newWord3);
}
}
Right now, it just takes the first letter of the string and adds it to the end. It doesn't change each word to pig latin, just the whole phrase. I was wondering of anyone could help me with this. THanks.
You need to use [i] to get items of your array :
var word = splitArray[i];
var newWord3 = word.substring(1,word.length) + word[0] + 'ay';
The best, if you want to end up with the whole new sentence, is to change each word an join them at the end :
var splitArray = whatWeTitle.split(" ");
for ( i = 0; i < splitArray.length; i++) {
var word = splitArray[i];
splitArray[i] = word.substring(1,word.length) + word[0] + 'ay';
}
var newSentence = splitArray.join(' ');
alert(newSentence);
If you test a little, you'll see this algorithm doesn't like the dots or comma in your sentence. If you want something stronger, you'd need a regular expression, for example like this :
var newSentence = whatWeTitle.replace(/[^\. ,]+/g, function(word){
return word.slice(1) + word[0] + 'ay';
});
alert(newSentence);
This works by replacing in place the words in the text, using a function to transform each word.
Something like this ?
function pigLatin(whatWeTitle) {
var alertThis = " ";
var splitArray = whatWeTitle.split(" ");
var finalString = "";
for ( i = 0; i < splitArray.length; i++) {
finalString += splitArray[i]+ "ay ";
}
alert(finalString);
}
pigLatin("this is a test");
You probably want to split off the first consonant values and then append them along with 'ay'.
I would use a regex to accomplish this. Here is a JSFiddle showing an example.
First part is split the word
var words = text.split(" ");
Next part is to piglatinify™ each word
words = words.map(function(word){ return pigLatinifyWord(word);});
This is the piglatinify™ function
function pigLatinifyWord(word){
var result;
var specialMatches = word.match(/(\W|\D)+$/);
var specialChars;
if(specialMatches && specialMatches.length >= 0){
var specialIndex = word.indexOf(specialMatches[0]);
specialChars = word.slice(specialIndex);
word = word.substr(0, specialIndex);
}
var i = word.search(/^[^aeiou]/);
if(i >= 0){
result = word.slice(i+1) + word.slice(0, i+1) + "ay";
}
else{
result = word + "ay";
}
if(specialChars){
result += specialChars;
}
return result;
}
Update
JSFiddle example now includes handling for non-word non-digit characters
var str = ' Some string ';
var output = str.replace(/^\s|\s(?=\s*$)/g , '_');
The output should look like this
'___Some string____'
This code works fine for the trailing whitespaces but all the leading whitespaces are replaced with just one underscore.
The working php regex for this is: /\G\s|\s(?=\s*$)/
Not pretty, but gets the job done
var str = " Some string ";
var newStr = str.replace(/(^(\s+)|(\s+)$)/g,function(spaces){ return spaces.replace(/\s/g,"_");});
This works but I don't like it:
var str = " some string ";
var result = str.replace(/^\s+|\s+$/g, function(m) {
return '________________________________________'.substring(0, m.length);
});
Or more flexibly:
var str = " some string ";
var result = str.replace(/^\s+|\s+$/g, function(m) {
var rv = '_',
n;
for (n = m.length - 1; n > 0; --n) {
rv += '_';
}
return rv;
});
That can be refined, of course.
But I like epascarello's answer better.
another reg ex
var str = " asdf "
str.replace(/^[ ]+|[ ]+$/g,function(spc){return spc.replace(/[ ]/g,"_")})
//"__asdf_______"
With String.prototype.repeat() the accepted answer can now be improved to
function replaceLeadingAndTrailingWhitespace(text, replace) {
return text.replace(/^\s+|\s+$/g, (spaces) => replace.repeat(spaces.length));
}