Trying to write a function which returns the calling string value converted to
lowercase. The trick is I can't use toLocaleLowerCase().
Below is what I have so far.
function charChange(char){
for (var i=0; i<char.length; i++){
var char2=charCodeAt(char[i])+32;
var char3=String.fromCharCode(char2);
if (char3 !== charCodeAt(97-122){
alert("Please enter only letters in the function")
}
}
return char;
}
To convert the uppercase letters of a string to lowercase manually (if you're not doing it manually, you should just use String.prototype.toLowerCase()), you must:
Write the boilerplate function stuff:
function strLowerCase(str) {
let newStr = "";
// TODO
return newStr;
}
Loop over each character of the original string, and get its code point:
function strLowerCase(str) {
let newStr = "";
for(let i = 0; i < str.length; i++) {
let code = str.charCodeAt(i);
// TODO
} return newStr;
}
Check if the character is an uppercase letter. In ASCII, characters with code points between 65 and 90 (inclusive) are uppercase letters.
function strLowerCase(str) {
let newStr = "";
for(let i = 0; i < str.length; i++) {
let code = str.charCodeAt(i);
if(code >= 65 && code <= 90) {
// TODO
} // TODO
} return newStr;
}
If the character is uppercase, add 32 to its code point to make it lowercase (yes, this was a deliberate design decision by the creators of ASCII). Regardless, append the new character to the new string.
function strLowerCase(str) {
let newStr = "";
for(let i = 0; i < str.length; i++) {
let code = str.charCodeAt(i);
if(code >= 65 && code <= 90) {
code += 32;
} newStr += String.fromCharCode(code);
} return newStr;
}
Test your new function:
strLowerCase("AAAAAAABBBBBBBCCCCCZZZZZZZZZaaaaaaaaaaa&$*(@&(*&*#@!");
// "aaaaaaabbbbbbbccccczzzzzzzzzaaaaaaaaaaa&$*(@&(*&*#@!"
charCodeAt() is a method called on a String, it's not a function. So you apply the method on a string and give the position of the character you want to convert as the parameter. Also as MultiplyByZer0 mentioned the word char is reserved: look at the list of reserved words.
The following code fixes the problem:
function charChange(str) {
var result = "";
for (var i = 0; i < str.length; i++) {
var code = str[i].charCodeAt(0);
if(code >= 65 && code <= 90) {
var letter = String.fromCharCode(code+32);
result += letter // append the modified character
} else {
result += str[i] // append the original character
}
}
return result;
}
console.log(charChange('j#aMIE'));These are the two most elegant solutions I can think of (at the moment). See comments within the code and don't hesitate to ask if anything is unclear.
function charChange1 (str) {
let result = '';
const len = str.length;
// go over each char in input string...
for (let i = 0; i < len; i++) {
const c = str[i];
const charCode = c.charCodeAt(0);
if (charCode < 65 || charCode > 90) {
// if it is not a uppercase letter,
// just append it to the output
// (also catches special characters and numbers)
result += c;
} else {
// else, transform to lowercase first
result += String.fromCharCode(charCode - 65 + 97);
}
}
return result;
}
function charChange2 (str) {
// Array.prototype.slice.call(str) converts
// an array-like (the string) into an actual array
// then, map each entry using the same logic as above
return Array.prototype.slice.call(str)
.map(function (c) {
const charCode = c.charCodeAt(0);
if (charCode < 65 || charCode > 90) return c;
return String.fromCharCode(charCode - 65 + 97);
})
// finally, join the array to a string
.join('');
}
console.log(charChange1("AAAAsfasSGSGSGSG'jlj89345"));
console.log(charChange2("AAAAsfasSGSGSGSG'jlj89345"));(On a side node, it would of course be possible to replace the magic numbers by constants declared as calls to 'A'.charCodeAt(0))
(A second side node: Don't use char since it is a reserved word in JavaScript; I prefer c)
You can use regex to convert the string to lower case:
:%s/.*/\L&/
const lowerCase = ()=>{
let welcome = prompt("Enter your string");
let lower = '';
for(let i=0; i<welcome.length;i++){
code = welcome.charCodeAt(i);
if(code >= 65 && code <= 90){
let co = code+32;
console.log(co);
lower += String.fromCharCode(co);
}
else
{
lower +=String.fromCharCode(code) ;
}
console.log(lower);
}
}
.toLowerCase()?charis a reserved word in JS that you are not allowed to use. Ifcharis an array (which it looks like), it should bechars.charCodeAt(97-122)becomescharCodeAt(-25), which makes no sense becauseString.prototype.charCodeAt()(1) must be called on a string and (2) takes an index, not a code point.charCodeAtis a method, not a function! You might want to dochar[i].charCodeAt(0)instead ofcharCodeAt(char[i])