Converting any string into camel case - javascript

How can I convert a string into camel case using javascript regex?
EquipmentClass name or
Equipment className or equipment class name or Equipment Class Name
should all become: equipmentClassName.

Looking at your code, you can achieve it with only two replace calls:
function camelize(str) {
return str.replace(/(?:^\w|[A-Z]|\b\w)/g, function(word, index) {
return index === 0 ? word.toLowerCase() : word.toUpperCase();
}).replace(/\s+/g, '');
}
camelize("EquipmentClass name");
camelize("Equipment className");
camelize("equipment class name");
camelize("Equipment Class Name");
// all output "equipmentClassName"
Edit: Or in with a single replace call, capturing the white spaces also in the RegExp.
function camelize(str) {
return str.replace(/(?:^\w|[A-Z]|\b\w|\s+)/g, function(match, index) {
if (+match === 0) return ""; // or if (/\s+/.test(match)) for white spaces
return index === 0 ? match.toLowerCase() : match.toUpperCase();
});
}

If anyone is using lodash, there is a _.camelCase() function.
_.camelCase('Foo Bar');
// → 'fooBar'
_.camelCase('--foo-bar--');
// → 'fooBar'
_.camelCase('__FOO_BAR__');
// → 'fooBar'

To get camelCase
ES5
var camalize = function camalize(str) {
return str.toLowerCase().replace(/[^a-zA-Z0-9]+(.)/g, function(match, chr)
{
return chr.toUpperCase();
});
}
ES6
var camalize = function camalize(str) {
return str.toLowerCase().replace(/[^a-zA-Z0-9]+(.)/g, (m, chr) => chr.toUpperCase());
}
> To get ***C**amel**S**entence**C**ase* or ***P**ascal**C**ase*
var camelSentence = function camelSentence(str) {
return (" " + str).toLowerCase().replace(/[^a-zA-Z0-9]+(.)/g, function(match, chr)
{
return chr.toUpperCase();
});
}
Note :
For those language with accents. Do include À-ÖØ-öø-ÿ with the regex as following
.replace(/[^a-zA-ZÀ-ÖØ-öø-ÿ0-9]+(.)/g This is only for one language. For another language, you have to search and find

I just ended up doing this:
String.prototype.toCamelCase = function(str) {
return str
.replace(/\s(.)/g, function($1) { return $1.toUpperCase(); })
.replace(/\s/g, '')
.replace(/^(.)/, function($1) { return $1.toLowerCase(); });
}
I was trying to avoid chaining together multiple replace statements. Something where I'd have $1, $2, $3 in my function. But that type of grouping is hard to understand, and your mention about cross browser problems is something I never thought about as well.

You can use this solution :
function toCamelCase(str){
return str.split(' ').map(function(word,index){
// If it is the first word make sure to lowercase all the chars.
if(index == 0){
return word.toLowerCase();
}
// If it is not the first word only upper case the first char and lowercase the rest.
return word.charAt(0).toUpperCase() + word.slice(1).toLowerCase();
}).join('');
}

In Scott’s specific case I’d go with something like:
String.prototype.toCamelCase = function() {
return this.replace(/^([A-Z])|\s(\w)/g, function(match, p1, p2, offset) {
if (p2) return p2.toUpperCase();
return p1.toLowerCase();
});
};
'EquipmentClass name'.toCamelCase() // -> equipmentClassName
'Equipment className'.toCamelCase() // -> equipmentClassName
'equipment class name'.toCamelCase() // -> equipmentClassName
'Equipment Class Name'.toCamelCase() // -> equipmentClassName
The regex will match the first character if it starts with a capital letter, and any alphabetic character following a space, i.e. 2 or 3 times in the specified strings.
By spicing up the regex to /^([A-Z])|[\s-_](\w)/g it will also camelize hyphen and underscore type names.
'hyphen-name-format'.toCamelCase() // -> hyphenNameFormat
'underscore_name_format'.toCamelCase() // -> underscoreNameFormat

Reliable, high-performance example:
function camelize(text) {
const a = text.toLowerCase()
.replace(/[-_\s.]+(.)?/g, (_, c) => c ? c.toUpperCase() : '');
return a.substring(0, 1).toLowerCase() + a.substring(1);
}
Case-changing characters:
hyphen -
underscore _
period .
space

function toCamelCase(str) {
// Lower cases the string
return str.toLowerCase()
// Replaces any - or _ characters with a space
.replace( /[-_]+/g, ' ')
// Removes any non alphanumeric characters
.replace( /[^\w\s]/g, '')
// Uppercases the first character in each group immediately following a space
// (delimited by spaces)
.replace( / (.)/g, function($1) { return $1.toUpperCase(); })
// Removes spaces
.replace( / /g, '' );
}
I was trying to find a JavaScript function to camelCase a string, and wanted to make sure special characters would be removed (and I had trouble understanding what some of the answers above were doing). This is based on c c young's answer, with added comments and the removal of $peci&l characters.

If regexp isn't required, you might want to look at following code I made a long time ago for Twinkle:
String.prototype.toUpperCaseFirstChar = function() {
return this.substr( 0, 1 ).toUpperCase() + this.substr( 1 );
}
String.prototype.toLowerCaseFirstChar = function() {
return this.substr( 0, 1 ).toLowerCase() + this.substr( 1 );
}
String.prototype.toUpperCaseEachWord = function( delim ) {
delim = delim ? delim : ' ';
return this.split( delim ).map( function(v) { return v.toUpperCaseFirstChar() } ).join( delim );
}
String.prototype.toLowerCaseEachWord = function( delim ) {
delim = delim ? delim : ' ';
return this.split( delim ).map( function(v) { return v.toLowerCaseFirstChar() } ).join( delim );
}
I haven't made any performance tests, and regexp versions might or might not be faster.

My ES6 approach:
const camelCase = str => {
let string = str.toLowerCase().replace(/[^A-Za-z0-9]/g, ' ').split(' ')
.reduce((result, word) => result + capitalize(word.toLowerCase()))
return string.charAt(0).toLowerCase() + string.slice(1)
}
const capitalize = str => str.charAt(0).toUpperCase() + str.toLowerCase().slice(1)
let baz = 'foo bar'
let camel = camelCase(baz)
console.log(camel) // "fooBar"
camelCase('foo bar') // "fooBar"
camelCase('FOO BAR') // "fooBar"
camelCase('x nN foo bar') // "xNnFooBar"
camelCase('!--foo-¿?-bar--121-**%') // "fooBar121"

This function by pass cammelcase such these tests
Foo Bar
--foo-bar--
__FOO_BAR__-
foo123Bar
foo_Bar
function toCamelCase(str)
{
var arr= str.match(/[a-z]+|\d+/gi);
return arr.map((m,i)=>{
let low = m.toLowerCase();
if (i!=0){
low = low.split('').map((s,k)=>k==0?s.toUpperCase():s).join``
}
return low;
}).join``;
}
console.log(toCamelCase('Foo Bar'));
console.log(toCamelCase('--foo-bar--'));
console.log(toCamelCase('__FOO_BAR__-'));
console.log(toCamelCase('foo123Bar'));
console.log(toCamelCase('foo_Bar'));
console.log(toCamelCase('EquipmentClass name'));
console.log(toCamelCase('Equipment className'));
console.log(toCamelCase('equipment class name'));
console.log(toCamelCase('Equipment Class Name'));

Here is a one liner doing the work:
const camelCaseIt = string => string.toLowerCase().trim().split(/[.\-_\s]/g).reduce((string, word) => string + word[0].toUpperCase() + word.slice(1));
It splits the lower-cased string based on the list of characters provided in the RegExp [.\-_\s] (add more inside the []!) and returns a word array . Then, it reduces the array of strings to one concatenated string of words with uppercased first letters. Because the reduce has no initial value, it will start uppercasing first letters starting with the second word.
If you want PascalCase, just add an initial empty string ,'') to the reduce method.

The top answer is terse but it doesn't handle all edge cases. For anyone needing a more robust utility, without any external dependencies:
function camelCase(str) {
return (str.slice(0, 1).toLowerCase() + str.slice(1))
.replace(/([-_ ]){1,}/g, ' ')
.split(/[-_ ]/)
.reduce((cur, acc) => {
return cur + acc[0].toUpperCase() + acc.substring(1);
});
}
function sepCase(str, sep = '-') {
return str
.replace(/[A-Z]/g, (letter, index) => {
const lcLet = letter.toLowerCase();
return index ? sep + lcLet : lcLet;
})
.replace(/([-_ ]){1,}/g, sep)
}
// All will return 'fooBarBaz'
console.log(camelCase('foo_bar_baz'))
console.log(camelCase('foo-bar-baz'))
console.log(camelCase('foo_bar--baz'))
console.log(camelCase('FooBar Baz'))
console.log(camelCase('FooBarBaz'))
console.log(camelCase('fooBarBaz'))
// All will return 'foo-bar-baz'
console.log(sepCase('fooBarBaz'));
console.log(sepCase('FooBarBaz'));
console.log(sepCase('foo-bar-baz'));
console.log(sepCase('foo_bar_baz'));
console.log(sepCase('foo___ bar -baz'));
console.log(sepCase('foo-bar-baz'));
// All will return 'foo__bar__baz'
console.log(sepCase('fooBarBaz', '__'));
console.log(sepCase('foo-bar-baz', '__'));
Demo here: https://codesandbox.io/embed/admiring-field-dnm4r?fontsize=14&hidenavigation=1&theme=dark

lodash can do the trick sure and well:
var _ = require('lodash');
var result = _.camelCase('toto-ce héros')
// result now contains "totoCeHeros"
Although lodash may be a "big" library (~4kB), it contains a lot of functions that you'd normally use a snippet for, or build yourself.

return "hello world".toLowerCase().replace(/(?:(^.)|(\s+.))/g, function(match) {
return match.charAt(match.length-1).toUpperCase();
}); // HelloWorld

Because this question needed yet another answer...
I tried several of the previous solutions, and all of them had one flaw or another. Some didn't remove punctuation; some didn't handle cases with numbers; some didn't handle multiple punctuations in a row.
None of them handled a string like a1 2b. There's no explicitly defined convention for this case, but some other stackoverflow questions suggested separating the numbers with an underscore.
I doubt this is the most performant answer (three regex passes through the string, rather than one or two), but it passes all the tests I can think of. To be honest, though, I really can't imagine a case where you're doing so many camel-case conversions that performance would matter.
(I added this as an npm package. It also includes an optional boolean parameter to return Pascal Case instead of Camel Case.)
const underscoreRegex = /(?:[^\w\s]|_)+/g,
sandwichNumberRegex = /(\d)\s+(?=\d)/g,
camelCaseRegex = /(?:^\s*\w|\b\w|\W+)/g;
String.prototype.toCamelCase = function() {
if (/^\s*_[\s_]*$/g.test(this)) {
return '_';
}
return this.replace(underscoreRegex, ' ')
.replace(sandwichNumberRegex, '$1_')
.replace(camelCaseRegex, function(match, index) {
if (/^\W+$/.test(match)) {
return '';
}
return index == 0 ? match.trimLeft().toLowerCase() : match.toUpperCase();
});
}
Test cases (Jest)
test('Basic strings', () => {
expect(''.toCamelCase()).toBe('');
expect('A B C'.toCamelCase()).toBe('aBC');
expect('aB c'.toCamelCase()).toBe('aBC');
expect('abc def'.toCamelCase()).toBe('abcDef');
expect('abc__ _ _def'.toCamelCase()).toBe('abcDef');
expect('abc__ _ d_ e _ _fg'.toCamelCase()).toBe('abcDEFg');
});
test('Basic strings with punctuation', () => {
expect(`a'b--d -- f.h`.toCamelCase()).toBe('aBDFH');
expect(`...a...def`.toCamelCase()).toBe('aDef');
});
test('Strings with numbers', () => {
expect('12 3 4 5'.toCamelCase()).toBe('12_3_4_5');
expect('12 3 abc'.toCamelCase()).toBe('12_3Abc');
expect('ab2c'.toCamelCase()).toBe('ab2c');
expect('1abc'.toCamelCase()).toBe('1abc');
expect('1Abc'.toCamelCase()).toBe('1Abc');
expect('abc 2def'.toCamelCase()).toBe('abc2def');
expect('abc-2def'.toCamelCase()).toBe('abc2def');
expect('abc_2def'.toCamelCase()).toBe('abc2def');
expect('abc1_2def'.toCamelCase()).toBe('abc1_2def');
expect('abc1 2def'.toCamelCase()).toBe('abc1_2def');
expect('abc1 2 3def'.toCamelCase()).toBe('abc1_2_3def');
});
test('Oddball cases', () => {
expect('_'.toCamelCase()).toBe('_');
expect('__'.toCamelCase()).toBe('_');
expect('_ _'.toCamelCase()).toBe('_');
expect('\t_ _\n'.toCamelCase()).toBe('_');
expect('_a_'.toCamelCase()).toBe('a');
expect('\''.toCamelCase()).toBe('');
expect(`\tab\tcd`.toCamelCase()).toBe('abCd');
expect(`
ab\tcd\r
-_
|'ef`.toCamelCase()).toBe(`abCdEf`);
});

To effectively create a function that converts the casing of a string to camel-case, the function will also need to convert each string to lower-case first, before transforming the casing of the first character of non-first strings to an uppercase letter.
My example string is:
"text That I WaNt to make cAMEL case"
Many other solutions provided to this question return this:
"textThatIWaNtToMakeCAMELCase"
What I believe should be the expected, desired output would be this though, where all the mid-string uppercase characters are first transformed to be lowercase:
"textThatIWanrtToMakeCamelCase"
This can be done WITHOUT using any replace() method calls, by utilizing the String.prototype.split(), Array.prototype.map(), and Array.prototype.join() methods:
≤ ES5 Version
function makeCamelCase(str) {
return str
.split(' ')
.map((e,i) => i
? e.charAt(0).toUpperCase() + e.slice(1).toLowerCase()
: e.toLowerCase()
)
.join('')
}
makeCamelCase("text That I WaNt to make cAMEL case")
// -> "textThatIWanrtToMakeCamelCase" ✅
I'll break down what each line does, and then provide the same solution in two other formats— ES6 and as a String.prototype method, though I'd advise against extending built-in JavaScript prototypes directly like this.
Explainer
function makeCamelCase(str) {
return str
// split string into array of different words by splitting at spaces
.split(' ')
// map array of words into two different cases, one for the first word (`i == false`) and one for all other words in the array (where `i == true`). `i` is a parameter that denotes the current index of the array item being evaluated. Because indexes start at `0` and `0` is a "falsy" value, we can use the false/else case of this ternary expression to match the first string where `i === 0`.
.map((e,i) => i
// for all non-first words, use a capitalized form of the first character + the lowercase version of the rest of the word (excluding the first character using the slice() method)
? e.charAt(0).toUpperCase() + e.slice(1).toLowerCase()
// for the first word, we convert the entire word to lowercase
: e.toLowerCase()
)
// finally, we join the different strings back together into a single string without spaces, our camel-cased string
.join('')
}
makeCamelCase("text That I WaNt to make cAMEL case")
// -> "textThatIWanrtToMakeCamelCase" ✅
Condensed ES6+ (One-Liner) Version
const makeCamelCase = str => str.split(' ').map((e,i) => i ? e.charAt(0).toUpperCase() + e.slice(1).toLowerCase() : e.toLowerCase()).join('')
makeCamelCase("text That I WaNt to make cAMEL case")
// -> "textThatIWanrtToMakeCamelCase" ✅
String.prototype method version
String.prototype.toCamelCase = function() {
return this
.split(' ')
.map((e,i) => i
? e.charAt(0).toUpperCase() + e.slice(1).toLowerCase()
: e.toLowerCase()
)
.join('')
}
"text That I WaNt to make cAMEL case".toCamelCase()
// -> "textThatIWanrtToMakeCamelCase" ✅

little modified Scott's answer:
toCamelCase = (string) ->
string
.replace /[\s|_|-](.)/g, ($1) -> $1.toUpperCase()
.replace /[\s|_|-]/g, ''
.replace /^(.)/, ($1) -> $1.toLowerCase()
now it replaces '-' and '_' too.

All 14 permutations below produce the same result of "equipmentClassName".
String.prototype.toCamelCase = function() {
return this.replace(/[^a-z ]/ig, '') // Replace everything but letters and spaces.
.replace(/(?:^\w|[A-Z]|\b\w|\s+)/g, // Find non-words, uppercase letters, leading-word letters, and multiple spaces.
function(match, index) {
return +match === 0 ? "" : match[index === 0 ? 'toLowerCase' : 'toUpperCase']();
});
}
String.toCamelCase = function(str) {
return str.toCamelCase();
}
var testCases = [
"equipment class name",
"equipment class Name",
"equipment Class name",
"equipment Class Name",
"Equipment class name",
"Equipment class Name",
"Equipment Class name",
"Equipment Class Name",
"equipment className",
"equipment ClassName",
"Equipment ClassName",
"equipmentClass name",
"equipmentClass Name",
"EquipmentClass Name"
];
for (var i = 0; i < testCases.length; i++) {
console.log(testCases[i].toCamelCase());
};

you can use this solution:
String.prototype.toCamelCase = function(){
return this.replace(/\s(\w)/ig, function(all, letter){return letter.toUpperCase();})
.replace(/(^\w)/, function($1){return $1.toLowerCase()});
};
console.log('Equipment className'.toCamelCase());

Here's my suggestion:
function toCamelCase(string) {
return `${string}`
.replace(new RegExp(/[-_]+/, 'g'), ' ')
.replace(new RegExp(/[^\w\s]/, 'g'), '')
.replace(
new RegExp(/\s+(.)(\w+)/, 'g'),
($1, $2, $3) => `${$2.toUpperCase() + $3.toLowerCase()}`
)
.replace(new RegExp(/\s/, 'g'), '')
.replace(new RegExp(/\w/), s => s.toLowerCase());
}
or
String.prototype.toCamelCase = function() {
return this
.replace(new RegExp(/[-_]+/, 'g'), ' ')
.replace(new RegExp(/[^\w\s]/, 'g'), '')
.replace(
new RegExp(/\s+(.)(\w+)/, 'g'),
($1, $2, $3) => `${$2.toUpperCase() + $3.toLowerCase()}`
)
.replace(new RegExp(/\s/, 'g'), '')
.replace(new RegExp(/\w/), s => s.toLowerCase());
};
Test cases:
describe('String to camel case', function() {
it('should return a camel cased string', function() {
chai.assert.equal(toCamelCase('foo bar'), 'fooBar');
chai.assert.equal(toCamelCase('Foo Bar'), 'fooBar');
chai.assert.equal(toCamelCase('fooBar'), 'fooBar');
chai.assert.equal(toCamelCase('FooBar'), 'fooBar');
chai.assert.equal(toCamelCase('--foo-bar--'), 'fooBar');
chai.assert.equal(toCamelCase('__FOO_BAR__'), 'fooBar');
chai.assert.equal(toCamelCase('!--foo-¿?-bar--121-**%'), 'fooBar121');
});
});

following #Scott's readable approach, a little bit of fine tuning
// convert any string to camelCase
var toCamelCase = function(str) {
return str.toLowerCase()
.replace( /['"]/g, '' )
.replace( /\W+/g, ' ' )
.replace( / (.)/g, function($1) { return $1.toUpperCase(); })
.replace( / /g, '' );
}

There is my solution:
const toCamelWord = (word, idx) =>
idx === 0 ?
word.toLowerCase() :
word.charAt(0).toUpperCase() + word.slice(1).toLowerCase();
const toCamelCase = text =>
text
.split(/[_-\s]+/)
.map(toCamelWord)
.join("");
console.log(toCamelCase('User ID'))

This method seems to outperform most answers on here, it's a little bit hacky though, no replaces, no regex, simply building up a new string that's camelCase.
String.prototype.camelCase = function(){
var newString = '';
var lastEditedIndex;
for (var i = 0; i < this.length; i++){
if(this[i] == ' ' || this[i] == '-' || this[i] == '_'){
newString += this[i+1].toUpperCase();
lastEditedIndex = i+1;
}
else if(lastEditedIndex !== i) newString += this[i].toLowerCase();
}
return newString;
}

This builds on the answer by CMS by removing any non-alphabetic characters including underscores, which \w does not remove.
function toLowerCamelCase(str) {
return str.replace(/[^A-Za-z0-9]/g, ' ').replace(/^\w|[A-Z]|\b\w|\s+/g, function (match, index) {
if (+match === 0 || match === '-' || match === '.' ) {
return ""; // or if (/\s+/.test(match)) for white spaces
}
return index === 0 ? match.toLowerCase() : match.toUpperCase();
});
}
toLowerCamelCase("EquipmentClass name");
toLowerCamelCase("Equipment className");
toLowerCamelCase("equipment class name");
toLowerCamelCase("Equipment Class Name");
toLowerCamelCase("Equipment-Class-Name");
toLowerCamelCase("Equipment_Class_Name");
toLowerCamelCase("Equipment.Class.Name");
toLowerCamelCase("Equipment/Class/Name");
// All output e

Upper camel case ("TestString") to lower camel case ("testString") without using regex (let's face it, regex is evil):
'TestString'.split('').reduce((t, v, k) => t + (k === 0 ? v.toLowerCase() : v), '');

I ended up crafting a slightly more aggressive solution:
function toCamelCase(str) {
const [first, ...acc] = str.replace(/[^\w\d]/g, ' ').split(/\s+/);
return first.toLowerCase() + acc.map(x => x.charAt(0).toUpperCase()
+ x.slice(1).toLowerCase()).join('');
}
This one, above, will remove all non-alphanumeric characters and lowercase parts of words that would otherwise remain uppercased, e.g.
Size (comparative) => sizeComparative
GDP (official exchange rate) => gdpOfficialExchangeRate
hello => hello

function convertStringToCamelCase(str){
return str.split(' ').map(function(item, index){
return index !== 0
? item.charAt(0).toUpperCase() + item.substr(1)
: item.charAt(0).toLowerCase() + item.substr(1);
}).join('');
}

I know this is an old answer, but this handles both whitespace and _ (lodash)
function toCamelCase(s){
return s
.replace(/_/g, " ")
.replace(/\s(.)/g, function($1) { return $1.toUpperCase(); })
.replace(/\s/g, '')
.replace(/^(.)/, function($1) { return $1.toLowerCase(); });
}
console.log(toCamelCase("Hello world");
console.log(toCamelCase("Hello_world");
// Both print "helloWorld"

const toCamelCase = str =>
str
.replace(/[^a-zA-Z0-9]+(.)/g, (m, chr) => chr.toUpperCase())
.replace(/^\w/, c => c.toLowerCase());

Related

Can this problem be solved using functional programming only?

The prompt was:
Create a function that takes in a string and returns a "URL version" of the string. This simply involves replacing the spaces with %20.
It asked to solve the problem using recursion and using .replace is not allowed.
Here is my solution but I understand the ouputArray is being mutated. Is there any other way to solve this without a mutation?
let inputString = "hello world I am fine";
let outputArray = [];
let stringToUrl = (inputString, n) => {
inputArray = [...inputString]
if(n < inputArray.length) {
if(inputArray[n] !== " ") {
outputArray.push(inputArray[n])
return stringToUrl(inputArray, n+1)
}
else {
outputArray.push("%20")
return stringToUrl(inputArray, n+1)
}
}
return outputArray.join('');
}
console.log(stringToUrl(inputString, 0))
Yes, you can do this with FP. In keeping with How do I ask and answer homework questions?, I won't reply with code, but with pointers.
If you weren't doing this with FP (but still had to write it yourself rather than using the string replace method, etc.), you'd probably use a loop building up a new string by looping through the original string character by character and either adding the original character to the new string or adding %20 to it.
In FP, loops are often done via recursion, and your instructions are to use recursion, so we'll do that instead.
Your function should handle the first character in the string it's given (either keeping it or replacing it with %20), and if that character is the only character, just return that updated "character;" otherwise, it should return the updated character followed by the result of passing the rest of the string (all but that first character) through your function again. That will work through the entire string via recursion, building up the new string. (No need for arrays, string concatenation and substring should be fine.)
Here I have made some changes to your code. Hope this solves your problem.
I don't have to use the second array but make changes to the original array.
let inputString = "hello world I am fine";
let stringToUrl = (inputString, n) => {
inputArray = [...inputString]
if(n < inputArray.length) {
if(inputArray[n] === " ") {
inputArray[n] = "%20"
return stringToUrl(inputArray, n+1)
}
else {
return stringToUrl(inputArray, n+1)
}
}
return inputArray.join('');
}
console.log(stringToUrl(inputString, 0))
const replace = (char: string) => char === ' ' ? '%20' : char;
const convert = (str: string, cache = ''): string => {
const [head, ...tail] = str;
return head
? convert(
tail.join(''),
cache.concat(replace(head))
)
: cache
}
const result = convert("hello world I am fine") // hello%20world%20I%20am%20fine
Playground
I hope this task is not language agnostic, because JS is not best choise in terms of recursion optimization.
One option to do that could be using a call to stringToUrl and use an inner recursive function making use of default parameters passing the values of the variables as function arguments.
For example using an arrow function, and also passing a function as a parameter that does a check to either add %20 to the array with final characters:
const stringToUrl = str => {
const func = (
s,
r = "",
c = s.charAt(0),
f = () => r += c === ' ' ? '%20' : c
) => s.length ? f() && func(s.substr(1), r) : r
return func(str)
}
console.log(stringToUrl("hello world I am fine"));
Output
hello%20world%20I%20am%20fine
const stringToUrl = str => {
const func = (
s,
r = "",
c = s.charAt(0),
f = () => r += c === ' ' ? '%20' : c
) => s.length ? f() && func(s.substr(1), r) : r
return func(str)
}
[
"",
" ",
" ",
"hello world I am fine"
].forEach(s =>
console.log(`[${s}] --> ${stringToUrl(s)}`)
);

how to capitalize every first letter with none before an apostrophe but with one after in javascript

In javascript, I need to capitalize each first letter of words in a string (proper name) but not when before an apostrophe such as this example :
from henri d'oriona --> Henry d'Oriona
All I can get is something like Henry D'oriona or best case Henry D'Oriona.
Thanks for your help
Jacques
You could use the String.replace method with a regular expression to produce a one-liner solution.
Note that String.replace can accept a function for its second argument which can be used to loop through the matches and modify them as necessary.
const specialCapitalize =
str => str.replace(/(\w[^\'])+/gi, word => word[0].toUpperCase() + word.slice(1));
console.log(specialCapitalize("henri d'oriona some other words"))
The regular expression /(\w[^\'])+/ is made up of a word character which is not followed by an apostrophe.
First case but to great was:
toTitleCase('henri d'oriona')
returns Henri D'orina
function toTitleCase(str) {
return str.replace(/\w\S*/g,
function(txt) {
return txt.charAt(0).toUpperCase() + txt.substr(1).toLowerCase();
}
);
}
and best case scenario returning "Henri D'Oriona"
function toProperCase(s) {
return s.toLowerCase().replace( /\b((m)(a?c))?(\w)/g,
function($1, $2, $3, $4, $5) { if($2){return $3.toUpperCase()+$4+$5.toUpperCase();}
return $1.toUpperCase(); });
}
Create a function which will make the first letter upperCase called capitalize.
After that, split the string by empty space and traverse the array obtained.
For each element from the resulted array apply capitalize :
let upperCase = capitalize(word);
Then join the values from array into one string.
const capitalize = (s) => {
if (typeof s !== 'string') return ''
let capitalWord = '';
if (s.includes("d'")) {
let nameAfterSpecialChar = s.split("d'")[1];
let capitalName = nameAfterSpecialChar.charAt(0).toUpperCase() + nameAfterSpecialChar.slice(1)
capitalWord = "d'" + capitalName
} else {
capitalWord = s.charAt(0).toUpperCase() + s.slice(1)
}
return capitalWord;
}
const makeNameWithCapital = (name) => {
var wordsList = name.split(" ");
let arrOfNames = []
for (let word of wordsList) {
let upperCase = capitalize(word);
arrOfNames.push(upperCase);
}
let nameWithUpper = arrOfNames.join(" ");
console.log(nameWithUpper)
return nameWithUpper;
}
const nameUnparsed= "henri d'oriona "
const nameUnparsed1 = "henri d'oriona d'example test"
makeNameWithCapital(nameUnparsed)
makeNameWithCapital(nameUnparsed1)
It's not the best solution from performance point of view, but you can use it as a start.

Convert a String to Spinal Case

Challenge: Convert a string to spinal case. Spinal case is all-lowercase-words-joined-by-dashes
function spinalCase(str) {
var res = str.replace(/\s/g, "-")
var result = res.replace(/_/g, '').toLowerCase();
return result;
}
Code works only if there are spaces between strings or if there are no underscores. I am stuck trying to pass the rest of the test-cases, does anybody else have any tips or ideas in mind?
spinalCase("This Is Spinal Tap") should return "this-is-spinal-tap".
spinalCase("thisIsSpinalTap") should return "this-is-spinal-tap".
spinalCase("The_Andy_Griffith_Show") should return "the-andy-griffith-show".
spinalCase("Teletubbies say Eh-oh") should return "teletubbies-say-eh-oh".
spinalCase("AllThe-small Things") should return "all-the-small-things".
You may remove all non-alphanumeric chars at the start/end of the string, replace these consecutive chars with - anywhere else, then you may insert a hyphen in between lower- and uppercase letters, and then turn all to lower case.
function spinalCase(str) {
return str.replace(/^[\W_]+|[\W_]+$|([\W_]+)/g, function ($0, $1) {
return $1 ? "-" : "";
}).replace(/([a-z])(?=[A-Z])/g, '$1-').toLowerCase();
}
console.log(spinalCase("This Is Spinal Tap")); // "this-is-spinal-tap".
console.log(spinalCase("thisIsSpinalTap")); // "this-is-spinal-tap".
console.log(spinalCase("The_Andy_Griffith_Show")); // "the-andy-griffith-show".
console.log(spinalCase("Teletubbies say Eh-oh")); //"teletubbies-say-eh-oh".
console.log(spinalCase("AllThe-small Things")); // "all-the-small-things".
Details
.replace(/^[\W_]+|[\W_]+$|([\W_]+)/g, function ($0, $1) { return $1 ? "-" : ""; }) - removes all non-alphanumeric chars at the start (^[\W_]+)/end ([\W_]+$) of the string, replace these consecutive chars with - anywhere else (([\W_]+))
.replace(/([a-z])(?=[A-Z])/g, '$1-') - insert a hyphen in between lower- and uppercase letters.
Answer for this question version: When input string use camel-case then we not need dictionary and can use regexp only:
let s="exampleStringTwoThe-smallThing";
let r=s.replace(/([A-Z][a-z\-]*)/g, ' $1');
console.log(r);
For current question version:
s.replace(/( |_)+/g,'-').replace(/([a-z])(?=[A-Z])/g, '$1-').toLowerCase()
function spinalCase(s) {
return s.replace(/( |_)+/g,'-').replace(/([a-z])(?=[A-Z])/g, '$1-').toLowerCase();
}
console.log( spinalCase("This Is Spinal Tap") ) // should return "this-is-spinal-tap".
console.log( spinalCase("thisIsSpinalTap") ) // should return "this-is-spinal-tap".
console.log( spinalCase("The_Andy_Griffith_Show") ) // should return "the-andy-griffith-show".
console.log( spinalCase("Teletubbies say Eh-oh") ) // should return "teletubbies-say-eh-oh".
console.log( spinalCase("AllThe-small Things") ) // should return "all-the-small-things".
I improve solution by remove on replace using Wiktor answer

Capitalize first letter of each word in JS

I'm learning how to capitalize the first letter of each word in a string and for this solution I understand everything except the word.substr(1) portion. I see that it's adding the broken string but how does the (1) work?
function toUpper(str) {
return str
.toLowerCase()
.split(' ')
.map(function(word) {
return word[0].toUpperCase() + word.substr(1);
})
.join(' ');
}
console.log(toUpper("hello friend"))
The return value contain 2 parts:
return word[0].toUpperCase() + word.substr(1);
1) word[0].toUpperCase(): It's the first capital letter
2) word.substr(1) the whole remain word except the first letter which has been capitalized. This is document for how substr works.
Refer below result if you want to debug:
function toUpper(str) {
return str
.toLowerCase()
.split(' ')
.map(function(word) {
console.log("First capital letter: "+word[0]);
console.log("remain letters: "+ word.substr(1));
return word[0].toUpperCase() + word.substr(1);
})
.join(' ');
}
console.log(toUpper("hello friend"))
Or you could save a lot of time and use Lodash
Look at
https://lodash.com/docs/4.17.4#startCase -added/edited-
https://lodash.com/docs/4.17.4#capitalize
Ex.
-added/edited-
You may what to use startCase, another function for capitalizing first letter of each word.
_.startCase('foo bar');
// => 'Foo Bar'
and capitalize for only the first letter on the sentence
_.capitalize('FRED');
// => 'Fred'
Lodash is a beautiful js library made to save you a lot of time.
There you will find a lot of time saver functions for strings, numbers, arrays, collections, etc.
Also you can use it on client or server (nodejs) side, use bower or node, cdn or include it manually.
Here is a quick code snippet. This code snippet will allow you to capitalize the first letter of a string using JavaScript.
function capitlizeText(word)
{
return word.charAt(0).toUpperCase() + word.slice(1);
}
The regexp /\b\w/ matches a word boundary followed by a word character. You can use this with the replace() string method to match then replace such characters (without the g (global) regexp flag only the first matching char is replaced):
> 'hello my name is ...'.replace(/\b\w/, (c) => c.toUpperCase());
'Hello my name is ...'
> 'hello my name is ...'.replace(/\b\w/g, (c) => c.toUpperCase());
'Hello My Name Is ...'
function titleCase(str) {
return str.toLowerCase().split(' ').map(x=>x[0].toUpperCase()+x.slice(1)).join(' ');
}
titleCase("I'm a little tea pot");
titleCase("sHoRt AnD sToUt");
The major part of the answers explains to you how works the substr(1). I give to you a better aproach to resolve your problem
function capitalizeFirstLetters(str){
return str.toLowerCase().replace(/^\w|\s\w/g, function (letter) {
return letter.toUpperCase();
})
}
Explanation:
- First convert the entire string to lower case
- Second check the first letter of the entire string and check the first letter that have a space character before and replaces it applying .toUpperCase() method.
Check this example:
function capitalizeFirstLetters(str){
return str.toLowerCase().replace(/^\w|\s\w/g, function (letter) {
return letter.toUpperCase();
})
}
console.log(capitalizeFirstLetters("a lOt of words separated even much spaces "))
Consider an arrow function with an implicit return:
word => `${word.charAt(0).toUpperCase()}${word.slice(1).toLowerCase()}`
This will do it in one line.
Using ES6
let captalizeWord = text => text.toLowerCase().split(' ').map( (i, j) => i.charAt(0).toUpperCase()+i.slice(1)).join(' ')
captalizeWord('cool and cool')
substr is a function that returns (from the linked MDN) a new string containing the extracted section of the given string (starting from the second character in your function). There is a comment on the polyfill implementation as well, which adds Get the substring of a string.
function titlecase(str){
let titlecasesentence = str.split(' ');
titlecasesentence = titlecasesentence.map((word)=>{
const firstletter = word.charAt(0).toUpperCase();
word = firstletter.concat(word.slice(1,word.length));
return word;
});
titlecasesentence = titlecasesentence.join(' ');
return titlecasesentence;
}
titlecase('this is how to capitalize the first letter of a word');
const capitalize = str => {
if (typeof str !== 'string') {
throw new Error('Invalid input: input must of type "string"');
}
return str
.trim()
.replace(/ {1,}/g, ' ')
.toLowerCase()
.split(' ')
.map(word => word[0].toUpperCase() + word.slice(1))
.join(' ');
};
sanitize the input string with trim() to remove whitespace from the leading and trailing ends
replace any extra spaces in the middle with a RegExp
normalize and convert it all toLowerCase() letters
convert the string to an array split on spaces
map that array into an array of capitalized words
join(' ') the array with spaces and return the newly capitalized string
Whole sentence will be capitalize only by one line
"my name is John".split(/ /g).map(val => val[0].toUpperCase() + val.slice(1)).join(' ')
Output "My Name Is John"
A nice simple solution, using pure JavaScript. JSFiddle
function initCap(s) {
var result = '';
if ((typeof (s) === 'undefined') || (s == null)) {
return result;
}
s = s.toLowerCase();
var words = s.split(' ');
for (var i = 0; i < words.length; ++i) {
result += (i > 0 ? ' ' : '') +
words[i].substring(0, 1).toUpperCase() +
words[i].substring(1);
}
return result;
}
Here is an example of how substr works: When you pass in a number, it takes a portion of the string based on the index you provided:
console.log('Testing string'.substr(0)); // Nothing different
console.log('Testing string'.substr(1)); // Starts from index 1 (position 2)
console.log('Testing string'.substr(2));
So, they are taking the first letter of each word, capitalizing it, and then adding on the remaining of the word. Ance since you are only capitalizing the first letter, the index to start from is always 1.
In word.substr(i), the param means the index of the word. This method cuts the word from the letter whose index equals i to the end of the word.
You can also add another param like word.substr(i, len), where len means the length of the character segmentation. For example:
'abcde'.substr(1, 2) → bc.
function toTitleCase(str)
{
return str.replace(/\w\S*/g, function(txt){return
txt.charAt(0).toUpperCase() + txt.substr(1).toLowerCase();});
}
Just map through if an array set the first letter as uppercase and concatenate with other letters from index 1.
The array isn't your case here.
const capitalizeNames = (arr) => {
arr.map((name) => {
let upper = name[0].toUpperCase() + name.substr(1)
console.log(upper)
})
}
Here's another clean way of Capitalizing sentences/names/... :
const capitalizeNames =(name)=>{
const names = name.split(' ') // ['kouhadi','aboubakr',essaaddik']
const newCapName = [] // declaring an empty array
for (const n of names){
newCapName.push(n.replace(n[0], n[0].toUpperCase()));
}
return newCapName.join(' ')
}
capitalizeNames('kouhadi aboubakr essaaddik'); // 'Kouhadi Aboubakr Essaaddik'
You could use these lines of code:
function toUpper(str) {
return [str.split('')[0].toUpperCase(), str.split('').slice(1, str.split('').length).join("")].join("")
}
Basically it will split all characters, slice it, create a new array without the first entry/character and replace the first entry/character with an uppercase verion of the character.
(Yes, this was tested and it works on Edge, Chrome and newer versions of Internet Explorer.)
This is probably not the greatest answer, but hopefully it works well enough for you.

Match exact word with new lines anywhere using JavaScript

How can I match following patterns using JavaScript programming language?
sample (not sample in sampleword)
sam\nple
sa\nmple
I used \b for boundaries for full word match.
I'm trying to find an efficient way to do newline match anywhere in the word.
For case 2: \bsam[\s\S]ple\b works.
The same can be adapted for case3 as well to match.
But, Is there a way to have single pattern match all of those ?
It looks like you're asking how to match a string with a single optional space anywhere in the string? If so, that looks like this:
function getRegEx(word) {
var patterns = word.split('').map(function (letter, index) {
return (
word.slice(0, index) +
'\\s?' +
word.slice(index)
)
})
patterns.shift()
return new RegExp('^' + patterns.join('|') + '$');
}
getRegEx('pattern').test('pat tern') // --> true
However, if there can be multiple spaces in the string (as in 's amp le'), then it would be as follows:
function getRegEx(word) {
word = word.split('')
word = word.map(function (letter) {
return letter + '\\s?'
})
return new RegExp('^' + word.join('') + '$')
}
getRegEx('pattern').test('pat tern') // --> true
Per OP's request (see comments):
If you want to look for an indefinite number of space characters, pass true to the following function (as the second param). Otherwise, it'll just find one:
function getRegEx(word, mult) {
var spaceCount = mult ? '*' : '?'
word = word.split('')
word = word.map(function (letter) {
return letter + '\\s' + spaceCount
})
return new RegExp('^' + word.join('') + '$')
}
getRegEx('pattern', true).test('pat tern') // --> true
If you wish to specify where in the pattern spaces may appear, that can be done as follows:
function getRegEx(word, mult) {
word = word.split('')
var spaceCount = mult ? '*' : '?'
var positions = []
word.forEach(function (char, index) {
if (char === ' ') positions.push(index)
})
positions.forEach(function (pos) {
word.splice(pos, 1, '\\s' + spaceCount)
})
return new RegExp('^' + word.join('') + '$')
}
Put a space in your pattern string wherever you want there to be spaces matched. As in:
getRegEx('p at tern', true).test('p at tern') // --> true
You can remove \n using replace and compare that to sample using word boundaries:
/\bsample\b/i.test('sa\nmple'.replace(/\n/g, ''))
true
/\bsample\b/i.test('sam\nple'.replace(/\n/g, ''))
true
/\bsample\b/i.test('sample'.replace(/\n/g, ''))
true
/\bsample\b/i.test('sample'.replace(/\n/g, ''))
true
/\bsample\b/i.test('some sam\nple'.replace(/\n/g, ''))
true
\bsample\b/i.test('sam\nples'.replace(/\n/g, ''))
false

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