Output with console.log
In the Hello World section, you experimented with displaying text on the screen. Technically, you sent the words to the console, which is a simple window where the user can type commands or view output. We used a print function without explicitly talking about how it works. Let’s fix that now.
We call the print function using the syntax
console.log(). When the code
runs, we want it to tell the computer, Please display what is inside the () on
the screen. For us, the words are enough - we want to LOG the text to the
CONSOLE. However, the computer only understands binary or hexadecimal
instructions. We need the compiler to change the keywords console and log
into a format that the machine understands.
ConsoleLogExamples01.js file in
how-to-write-code. Run the code with
node consolelogexamples01.js and note the difference between the
Observations line by line:
- In the line 1, we print some text, which is surrounded by quotes.
- In the line 2, we print a number. Note the absence of quote marks.
- In line 3, we use four words, separated by commas, all within the same
set of parentheses
(). When these four words print, they show up on the same line but separated by spaces.
- The code in line 4 puts extra spaces after the commas. How does this affect the output?
- Line 5 also prints more words, but in this case the code uses
+instead of a comma. The result is to print the words without spaces in between.
- Line 6 prints text and a number with a space in between.
Two Special Characters
One final observation for all of the examples above is that each time we use
console.log, a newline is inserted after the printed content. Think of
a newline as the same as hitting the Enter or Return key on your keyboard. The
cursor moves to the beginning of the next line.
For the computer, newline is an invisible character that is used to tell the
machine to move to the next line. It is possible to use this invisible
character with the special representation
Experiment with the newline character by opening up
ConsoleLogExamples02.js and running the code.
In addition to the newline character, there is also a special tab character,
\t. Go back to the eight examples above and experiment with using