Scratch JS Tutorial Forum

MegaApuTurkUltra

AmazingMech2418 wrote:
Then why is typescript not available on all devices? JavaScript is a great language.

You know what else is available on all devices?

C

MollTheCoder

AmazingMech2418 wrote:
JS basics #1

JavaScript is a common programming language for web and game programming. It includes variables and functions. It is case sensitive.
You define variables like this:
var a = "hi";
You have to put the semicolon at the end.
You define functions like this:
function myFunction() {
code
}
or
var myFunction = function() {
code
}
There are also alert boxes that use the alert() function, but that will be described more in JS basics #2.

You do not need semicolons for everything, but some things might need them. JavaScript has an automatic semicolon system. But, some people consider it good practice to add semicolons.

Sheep_maker

Apart from the three statement for loop, semicolons also obligatory before lines that start with (, `, [, and *.

const four = 4
 
(async () => {
  await confirmIsFour(four)
})()

JavaScript will assume that you're trying to call 4 as a function, with the async arrow function as a parameter, which will throw an error since 4 is not a function

const four = 4
 
`Four is also written as ${four}`.split('').forEach(char => {
  console.log(`**${char}** `)
})

JavaScript thinks that you're calling a tagged template literal, but since 4 isn't a function, it'll throw an error

const four = 4
 
[1, 2, 3, four].forEach(num => {
  console.log(num * num)
})

JavaScript assumes that you're trying to get a property of 4. It'll try to get 4[4] since the comma operator returns the final value, and since it's undefined, trying to get .forEach will throw an error.

class Four {
  value = 4
 
  * generateFourFours () {
    yield this.value
    yield this.value
    yield this.value
    yield this.value
  }
}

JavaScript thinks you're trying to multiply 4 in the class field by some value rather than interpreting the asterisk as an indication of a generator function, but it throws a syntax error elsewhere because a curly bracket doesn't make sense when following a function call

Standard requires a semicolon before each line starting with those characters to prevent this except for the last case since class fields are fairly new

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