Declaring Variables
Variables in JavaScript are containers for storing data values. The following statement declares the variable hello:
var catsounds;
Once variables are declared, they can be assigned to a value:
var catSounds;
catSounds = "meow";
The catSounds variable is now assigned to the value "meow". We can confirm this with console.log():
console.log(catSounds); // prints "meow" to the console
Variables can be declared and assigned in a single line of code:
var bestNumber = 8;
The statement above is equivalent to these two statements:
var bestNumber;
bestNumber = 8;
Once a variable is declared, it does not need to be re-declared. That is, you do not need to repeat the var symbol when re-assigning a variable to a new value. The following code is bad:
var sad;
var sad = "this code sucks"; // sad was already declared! This is bad!
This is much better:
var happy;
happy = ":-)";
| Question | Click to View Answer |
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Declare the variable iAmSilly. |
var iAmSilly;
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Declare the variable goodPlayer and assign it to the value "Steve Kerr". |
var goodPlayer;
goodPlayer = "Steve Kerr";
The goodPlayer variable can also be declared and assigned on a single line: var goodPlayer = "Steve Kerr";
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Assign the variable x to the value 3 and assign the variable y to the value 5. Print the sum of x and y to the console. |
var x = 3;
var y = 5;
console.log(x + y);
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