Capitalize first letter of each word in JS

Question

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 a

Answer 1

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"))

Answer 2

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.

Answer 3

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"

Answer 4

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.

Answer 5

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");

Answer 6

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)
})

}