String Data Type

Backticks

Allows to span multiple lines. And embedding a variable by using ${}.

Tagged Template

This is another interesting construct in javascript which I have not seen in any other language, basically we can manipulate using a function how the ${} variables are processed and return a specialied string.

let person = 'Mike';
let age = 28;

function myTag(strings, personExp, ageExp) {
  let str0 = strings[0]; // "That "
  let str1 = strings[1]; // " is a "
  let str2 = strings[2]; // "."

  let ageStr;
  if (ageExp > 99){
    ageStr = 'centenarian';
  } else {
    ageStr = 'youngster';
  }

  // We can even return a string built using a template literal
  return `${str0}${personExp}${str1}${ageStr}${str2}`;
}

let output = myTag`That ${ person } is a ${ age }.`;

console.log(output);
// That Mike is a youngster.

Source: Mozilla Developer Notes

length property not method

As the heading suggest, length in javascript is a property not a method. That is to access the lenght of a string one need to use str.length not str.lenght() as there is in another languages (like C++).

for..of

Instead of using for..in like we do in the case of iterating over the object keys, for..of is used to iterate over the characters present in the string.

~ bitwise NOT operator

1. It converts the number to a 32-bit integer
2. Removes the decimal part
3. Toggles all bits in binary representation

For 32-bit integers this means that ~n == -(n+1). This means that ~-1 = 0 which one can use to check if the output of some function is -1 or not.

for (let i = n; ~n; --n) {}

For example, the above loop will iterate [n..0].

Comparison

Lowercase is always greater than uppercase. This is because characters are internally represented as UTF-16.

Vocabulary

Diacritical marks: example Ö.