130 lines
3.3 KiB
Markdown
130 lines
3.3 KiB
Markdown
---
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title: Arithmetic Operation
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---
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JavaScript provides the user with five arithmetic operators: `+`, `-`, `*`, `/` and `%`. The operators are for addition, subtraction, multiplication, division and remainder respectively.
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## Addition
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**Syntax**
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`a + b`
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**Usage**
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2 + 3 // returns 5
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true + 2 // interprets true as 1 and returns 3
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false + 5 // interprets false as 0 and returns 5
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true + "bar" // concatenates the boolean value and returns "truebar"
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5 + "foo" // concatenates the string and the number and returns "5foo"
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"foo" + "bar" // concatenates the strings and returns "foobar"
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_Hint:_ There is a handy <a href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators#Increment' target='_blank' rel='nofollow'>increment</a>(++) operator that is a great shortcut when you're adding numbers by 1.
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## Subtraction
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**Syntax**
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`a - b`
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**Usage**
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2 - 3 // returns -1
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3 - 2 // returns 1
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false - 5 // interprets false as 0 and returns -5
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true - 3 // interprets true as 1 and returns -2
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5 - "foo" // returns NaN (Not a Number)
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_Hint:_ There is a handy <a href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators#Decrement_(--' target='_blank' rel='nofollow'>decrement</a>(--) operator that is a great shortcut when you're subtracting numbers by 1.
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## Multiplication
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**Syntax**
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`a * b`
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**Usage**
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2 * 3 // returns 6
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3 * -2 // returns -6
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false * 5 // interprets false as 0 and returns 0
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true * 3 // interprets true as 1 and returns 3
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5 * "foo" // returns NaN (Not a Number)
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Infinity * 0 // returns NaN
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Infinity * Infinity // returns Infinity
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## Division
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**Syntax**
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`a / b`
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**Usage**
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3 / 2 // returns 1.5
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3.0 / 2.0 // returns 1.5
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3 / 0 // returns Infinity
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3.0 / 0.0 // returns Infinity
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-3 / 0 // returns -Infinity
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false / 5 // interprets false as 0 and returns 0
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true / 2 // interprets true a 1 and returns 0.5
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5 / "foo" // returns NaN (Not a Number)
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Infinity / Infinity // returns NaN
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## Remainder
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**Syntax**
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`a % b`
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**Usage**
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3 % 2 // returns 1
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true % 5 // interprets true as 1 and returns 1
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false % 4 // interprets false as 0 and returns 0
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3 % "bar" // returns NaN
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## Increment
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**Syntax**
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`a++, ++a or a+=`
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**Usage**
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// Postfix
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x = 3; // declare a variable
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y = x++; // y = 4, x = 3
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// Prefix
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var a = 2;
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b = ++a; // a = 3, b = 3
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// Advanced
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var a = 4;
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var b = 5;
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a += b; //a = 9, b = 5
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## Decrement
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**Syntax**
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`a--, --a or a-=`
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**Usage**
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// Postfix
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x = 3; // declare a variable
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y = x--; // y = 3, x = 3
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// Prefix
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var a = 2;
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b = --a; // a = 1, b = 1
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// Advanced
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var a = 9;
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var b = 4;
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a -= b; //a = 5, b = 4
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_!Important!_ As you can see, you **cannot** perform any sort of operations on `Infinity`.
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Source: The amazing <a href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators' target='_blank' rel='nofollow'>MDN</a>.
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