When The Final Value Of An Expression Is Assigned To A Variable, It Will Be Converted To

As JavaScript developers, we are expected to know when values are compatible, or when one value type can be changed to another. This is crucial in programming because we want our code to run smoothly and correctly!

Variable values can be declared as numbers or strings. Numbers can be floating point or integers. Floating point numbers have decimal places, like 5.5 or 4.9; whereas, integers do not, like 5 or 9.

When assigning a value to a variable, if the value is a number, it will be converted to a string. If the value is not a number, it will be assigned as undefined. These are both unexpected results that could cause problems in your code.

In this article, we will discuss more about these conversions and how to fix them so that your code runs smoothly.

What happens when the final value of an expression is assigned to a variable?

When the final value of an expression is assigned to a variable, it will be converted to its literal value.

For example, let’s say you have a variable called number and you calculate the value 5 + 2 * 2. You then assign the result to the same variable number.

In this case, the variable number would end up with the literal value of 5 + 2 * 2, or 8. The reason for this is because when an expression is assigned to a variable, JavaScript converts it to its literal value.

Since the expression was already calculated and equated to 8, that is what gets assigned to the variable number. There is no re-calculation happening on assignment.

You can try this out yourself by putting some simple code in a file and running it in the browser.

Convertible types

When an expression is assigned to a variable, the variable must be able to hold the value of the expression.

If the expression is of a type that cannot be converted to the type of the variable, then the assignment will not happen. For example, if we try to assign a number to a string variable, then nothing will happen because strings cannot be converted to numbers.

Conversions can happen in either direction: from a string to a number, or from a number to a string. In both cases, there must be some way to do it so that the assignment happens.

When var = 5; , then var is now declared as a new variable with the type language|nounstring .There can never be a number that is declared as a string, so this implicit conversion happens.

When var = “5” ; , then var is now declared asa new variable withthetypelanguage|nounnumber . There can never be a country namethat

is declared as a noun, so this implicit conversion happens.

In short: An implicit conversion from one type to another can happen when an expression is assignedtoa variable.

When this happens,thevariableisconvertedtothe final value ofthe expression. The exact nature of this conversion depends on what kind of expressions are being assigned and what kindsofvariablesarebeingassignedtothem.

When an expression has no value (such as void ) and gets assignedtoavariableofanothertype(suchasvoid5=5; ),thenitisthevalueoftheexpressionthatgetsignored(5).

More precisely, any implicit conversion from one type to another can happen when an expression is assignedtoavariable.

But what if there were no such conversions? What would happen? Let’s find out!

Conversions Are Not Always Happening

“Is This Happening?” – Korg Confusion Circuit No. 603XA (prototype) Final Test Log Entry.

“No!” – Drumbot Prototype No. 1257F Test Log Entry.

“It Is Not!” – Korg Confusion Circuit No. 603XA Final Test Log Entry.

…More content below…

Integers and floating-point numbers

As mentioned earlier, all JavaScript values are typed. This means that each value has a specific type, such as string, number, or object.

All variables in JavaScript are of the variable type. A variable can contain a string, number, or object value. You can check this by logging the variable to the console in the DevTools.

When you assign the final value of an expression to a variable, that variable will be converted to a string. If the expression is not a string already, it will be coerced (or changed) to a string. Coercion is when one type of value is changed to another type of value.

For example:

var x = 3 + 4; // The final value of the expression (8) is assigned to x var y = x; // The final value of x (8) is assigned to y

var z = "Hello"; var w = z + " World!"; // z is converted to a string and then concatenated with World!

var v = new Object(); var u = v + {key:"value"}; // v is converted to a string and then Object() is appended to it

var s = [1, 2]; var t = s + ["3", 4]; // s is converted to a string and then [1, 2] is appended to it

.

Strings

In Flutter, strings are a special type that represents text. Strings can be used to represent

things like text entered by the user, text displayed on a screen, or text stored in a database.

As you have seen so far, strings can be created using the String constructor, with double quotes: String(“A String”) . You can also create strings using triple single quotes: ‘This is a string’.

You can add values to strings in several ways. The most common way is to use the + operator: ‘this is a string’ + ‘another string’. You can also use append() , insert() , and concatenation (+=). All of these will be covered in detail later in this chapter.

When the final value of an expression is assigned to a variable, it will be converted to a string by default.

Booleans

In Flutter, Boolean values are represented by the bool type. A Boolean value is a value that is either true or false.

The bool type in Flutter is a String type, which means it is a data type that represents textual information. A String can either be a word, sentence, paragraph, or anything that can be expressed in those forms.

As mentioned before, all types in Flutter have a built-o conversion to and from each other. When the final value of an expression is assigned to a variable, it will be converted to the appropriate type of that variable.

For example, if we had a boolean variable named varValue and we assigned the expression true to it, then it would be set to the boolean value true. If we assigned 2 + 2 = 4 to it then it would be set to 4.

Null value

When an expression is assigned to a variable, the value of the expression is what is stored in the variable. If the expression is not defined, then it returns null , which is not a value, but rather undefined .

Variables can be defined as either a String type or a Boolean type. A String type variable can hold any string of characters, like “hello” or “2 + 2 = 4.” A Boolean type variable can only hold true or false .

When an expression that returns null or undefined is assigned to a String or Boolean type variable, JavaScript will automatically convert it to the corresponding string or boolean value.

For example, if you assign the expression 2 + 2 = 4 to the variable truth , then it will be converted to true .

Unknown values and undefined values

As mentioned earlier, in JavaScript, values can either be undefined or null. These values are called primitive values.

Primitive values are built-up from atoms, which are the smallest units of a type. For example, a number is composed of its value and its type (such as integer or decimal).

Atoms can also be strings (which are a sequence of characters) or booleans (which can only be true or false).

When you try to assign an expression to a variable that contains a primitive value, the compiler will complain. It will ask you whether you intended to assign the value or the variable itself. You must tell it that you intended to assign the value itself.

For instance, let’s try assigning the string “hello” to a variable named var1:var1 = “hello”; //Compiler error!You must tell it that you intended to assign “hello” itself:var1 = “hello”The compiler will then allow this assignment.

Type conversion in JavaScript

When an expression is assigned to a variable, the value of that expression is converted to the type of the variable.

For example, if x is 5 and y is 10, then x + y is not 15 (a number) but rather 5 + 10 = 15 (two numbers).

This happens because variables are declared as a specific type of value, so JavaScript needs to figure out how to convert the expression to the correct type.

It does this by using a process called type conversion. Type conversion rules vary depending on what type you are converting to.

Here are some examples: Type Conversion Rules For Numbers

• If the value inside the variable is a number, then it will be unchanged when assigned to the variable.

• If the value inside the variable is NaN, then it will be converted to null when assigned to the variable.

• If the value inside the variable is null, then it will be converted to 0 when assigned to the variable.

• If the variable is undefined, then it will be converted to NaN when assigned to thevariable.