Lambda function in the JavaScript . Use the lambda function. [Example1] var myFunc1 = (a, b) => a + b; [Example2] Calculate(15, 7, (v1, v2) => {return v1+v2;});

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Lambda function in the JavaScript . Use the lambda function. [Example1] var myFunc1 = (a, b) => a + b; [Example2] Calculate(15, 7, (v1, v2) => {return v1+v2;}); | standard ES5

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Lambda function in the JavaScript | standard ES5

last updated: 1 Augusta 2020

Lambda function denoted by =>

Lambda function is a shortened version of the unnamed function.

The lambda function is used in the same way as the unnamed function. The unnamed function is used as follows:
• we pass the unnamed function as a parameter to another function... Example: Calculate(15, 7, function(v1, v2) {return v1+v2;});
• create a new variable and assign an unnamed function to the new variable... Example: var myFunc1 = function (a, b) { return a + b; } ;

The Lambda function is described as follows:

Lambda function:

JavaScript

() => 30

Lambda function without parameters

The lambda function returns: 30

Lambda function without body function

Full example:

Html

<html>
<body>

<script>
     // declare lambda function
     var myFunc1 = () => 30;

     // call the function
     var result = myFunc1();

     // result = 30
</script>

</body>
</html>

Lambda function:

JavaScript

() => {
return 30;
}

Lambda function without parameters

The lambda function returns: 30

Lambda function with body function
{
...
}
the function body allows you to use many lines of code

Full example:

Html

<html>
<body>

<script>
     // declare lambda function
     var myFunc1 = () => {
          return 30;
     };

     // call the function
     var result = myFunc1();

     // result = 30
</script>

</body>
</html>

Lambda function:

JavaScript

value1 => value1 * 5

Lambda function with 1st parameter
value1

The lambda function returns: value1 * 5

Lambda function without body function

Full example:

Html

<html>
<body>

<script>
     // declare lambda function
     var myFunc1 = value1 => value1 * 5;

     // call the function
     var result = myFunc1(10);

     // result = 50
</script>

</body>
</html>

Lambda function:

JavaScript

value1 =>
{
return value1 * 5;
}

Lambda function with 1st parameter
value1

The lambda function returns: value1 * 5

Lambda function with body function
{
...
}
the function body allows you to use many lines of code

Full example:

Html

<html>
<body>

<script>
     // declare lambda function
     var myFunc1 = value1 =>
     {
          return value1 * 5;
     };

     // call the function
     var result = myFunc1(10);

     // result = 50
</script>

</body>
</html>

Lambda function:

JavaScript

(value1, value2) => value1 + value2

Lambda function with 2 parameters
value1, value2

The lambda function returns: value1 + value2

Lambda function without body function

Full example:

Html

<html>
<body>

<script>
     // declare lambda function
     var myFunc1 = (value1, value2) => value1 + value2;

     // call the function
     var result = myFunc1(10, 30);

     // result = 40
</script>

</body>
</html>

Lambda function:

JavaScript

(value1, value2) =>
{
return value1 + value2;
}

Lambda function with 2 parameters
value1, value2

The lambda function returns: value1 + value2

Lambda function with body function
{
...
}
the function body allows you to use many lines of code

Full example:

Html

<html>
<body>

<script>
     // declare lambda function
     var myFunc1 = (value1, value2) =>
     {
          return value1 + value2;
     };

     // call the function
     var result = myFunc1("Evgen", "123");

     // result = "Evgen123"
</script>

</body>
</html>

Lambda function:

JavaScript

(userName, userAge) => ({name: userName, age: userAge})

Lambda function with 2 parameters
userName, userAge

The Lambda function returns an object with the following properties: name and age
{name: userName, age: userAge}

Lambda function without body function

Note!
We return an object
({name: userName, age: userAge})
in parentheses ( ... )
to tell the compiler that we don't have a function body.

Full example:

Html

<html>
<body>

<script>
     // declare lambda function
     var myFunc1 = (userName, userAge) => ({name: userName, age: userAge});

     // call the function
     var result = myFunc1("Evgen", "123");

     // result.name = "Evgen"
     // result.age = 123
</script>

</body>
</html>

Lambda function:

JavaScript

comp => ({price: 10, comp})

Lambda function with one parameter
comp

The Lambda function returns an object with the following properties: price and comp
{price: 10, comp} // comp the output parameter is equal to the input parameter

Lambda function without body function

Note!
We return an object
({price: 10, comp})
in parentheses ( ... )
to tell the compiler that we don't have a function body.

Full example:

Html

<html>
<body>

<script>
     // declare lambda function
     var myFunc1 = comp => ({price: 10, comp});

     // call the function
     var result = myFunc1(123);

     // result.price = 10
     // result.comp = 123
</script>

</body>
</html>

Lambda function:

JavaScript

(userName, userAge) => {
return {name: userName, age: userAge};
}

Lambda function with 2 parameters
userName, userAge

The Lambda function returns an object with the following properties: name and age
{name: userName, age: userAge}

Lambda function with body function
{
...
}
the function body allows you to use many lines of code

Full example:

Html

<html>
<body>

<script>
     // declare lambda function
     var myFunc1 = (userName, userAge) => {
          return {name: userName, age: userAge};
     };

     // call the function
     var result = myFunc1("Evgen", "123");

     // result.name = "Evgen"
     // result.age = 123
</script>

</body>
</html>

Example1. Create a new variable and assign a lambda function to the new variable

JavaScript

<html>
<body>

<script>

     // declare an unnamed function with 2 parameters and returning a + b
     var myFunc1 = (a, b) => a + b;

     // call an unnamed function
     var value = myFunc1(15, 7);
     // value = 22

</script>

</body>
</html>

Explanation

JavaScript

// create a new variable myFunc1
var myFunc1

JavaScript

// myFunc1 variable assign an unnamed function with 2 parameters and returning a + b
myFunc1 = (a, b) => a + b;

Example2. We pass the lambda function as a parameter to another function

Html

<html>
<body>

<script>
     // Function declaration Calculate
     function Calculate(a, b, funcFormula) // parameter funcFormula there is a function because it is used as a function
     {
          return funcFormula(a, b);
     }
</script>

<script>
     // Call the function Calculate
     var value = Calculate(15, 7, (value1, value2) => // it is a lambda function that counts summation
          {
               return value1 + value2;
          }
     );
     // value = 22

     // Call the function Calculate
     var value = Calculate(23, 12, (value1, value2) => // it is a lambda function that counts subtraction
          {
               return value1 - value2;
          }
     );
     // value = 11
</script>

</body>
</html>

Explanation

In the example, call the function Calculate
Calculate(15, 7, (value1, value2) =>
     {
            return value1 + value2;
     }
);

Attention! Blue flagged lambda function

In the function Calculate
1st parameter pass the number 15
With the 2nd parameter we pass the number 7
With the 3rd parameter we pass the lambda function
(value1, value2) =>
{
     return value1 + value2;
}

value1 1st lambda function parameter
value2 2nd parameter lambda function

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