Here's one we've learned already:
> "supercalifragilisticexpialidocious".toUpperCase(); "SUPERCALIFRAGILISTICEXPIALIDOCIOUS"
Here's the opposite of
toUpperCase, making a string all lower case:
> "HOWDY, NEIGHBOR".toLowerCase(); "howdy, neighbor"
Here's the other string method we've learned - a method so important that we recommend memorizing it (though you can always look up the documentation if you need to):
> const word = "foo"; undefined > word.concat("bar"); "foobar"
Some string methods take numbers as arguments. Here's an example:
> "caterpillar".charAt(5); "p"
This method turns a number into a string.
> const myBirthday = 42; > const myStringifiedBirthday = myBirthday.toString(); "42"
We can also call
toString on a number instead of a variable:
> 42.34.toString(); "42.34" > 42..toString(); "42"
Note that you need to add the decimal point after a whole number before you can call
toString on it! So that means, there are two decimal points.
This method returns a string with only the number of decimal points that is specified in the argument. If you want 1 decimal point, and your number has 3, then
toFixed will chop off the extra decimal points, leaving only 1. Note that this method is called on a number, but turns the number into a string.
> 42.222.toFixed(1); '42.2' > const myFavRealNumber = 3.14; > myFavRealNumber.toFixed(0); '3'
Methods can be chained like this:
> "foo".concat("bar").toUpperCase(); "FOOBAR"
We actually tried out chaining these exact string methods when we discussed the distinction between methods and functions. As we can see, when we chain methods together like this, we first concatenate the string and then uppercase that string.
Here's an example of chaining number methods:
> 4.3354.toFixed(2).toString(); "4.34"
In this example, we are first executing
toFixed on the number, and then we're turning it onto a string with
toString. Take note, it is redundant to call
toFixed returns a string anyways.
+ operator lets us do addition if we're working with numbers, or concatenation if we're working with strings. Using the
+ with numbers should be familiar:
> 1 + 3 4
Let's take a look at using
+ with strings:
> "I love" + " " + "Epicodus"; "I love Epicodus"
As we can see, we can just use the
+ sign to "add" strings together! This has the same effect as the
And we can do this with variables, too:
> const sentiment = "I love "; undefined > const animal1 = "cats"; undefined > const animal2 = "dogs"; undefined > sentiment + animal1; "I love cats" > sentiment + animal2; "I love dogs"
Or with variables holding numbers:
> const number1 = 1; undefined > const number2 = 99; undefined > number1 + number2; 100
Now, check out this more complex example, where we include a variable with a method called on it:
> const myBirthday = 42; > const aboutMe = "I am " + myBirthday.toString() + " and I was born in '79."; > aboutMe; "I am 42 and I was born in 1979."
Here's the same example written in a different way:
> "I am " + 42.toString() + " and I was born in '79."; "I am 42 and I was born in 1979."
concat(). This is still known as concatenation despite not using the
"I love" + " " + "Epicodus";
A few useful string methods:
charAt();- Returns the character at a particular location in a String.
toUpperCase();- Converts a string to uppercase.
toLowerCase();- Converts a string to lowercase.
concat();- Combines two strings.
A few useful number methods:
toString();- Converts a number into a string.
toFixed();- Converts a number into a string with only the number of decimal points that is specified in the argument.
You can call methods on strings or numbers, or variables assigned to strings or numbers:
"supercalifragilisticexpialidocious".toUpperCase(); const word = "foo"; word.concat("bar");
You might wonder how we were able to use
concat with a constant, but this method (and most others) doesn't change what's known as the receiver - the thing that a method is being called on. In the example above,
word is the receiver. And if we check the value of
word, it's still
"foobar". We would need to assign the return value of the expression above to a new variable for
"foobar" to be saved.
Lesson 13 of 65
Last updated May 23, 2022