JavaScript For In Loop

On 4 minutes, 37 seconds read By Edward

For In Loop In JavaScript

Loops execute one or more statements up to a specific number of times.

Loops allow repetitive tasks to be executed using minimal code. For in loop iterates over the enumerable properties on an object.

Loops allow complex tasks to be simplified by automating similar operations.

Common Syntax For In Loop In JavaScript

Common For In Loop Conditions

Ojamboshop.com Learning JavaScript For In Loop
Name Description Example
for (key in object) loop assigns object key for (let key in pickup_truck)
for (key in array) loop assigns array key for (let n in even_numbers)
break End execution of current structure break;
continue Skip rest of current loop iteration continue;
Name Description Example

JavaScript For In Loop Snippet

// OjamboShop.com Learning JavaScript For In Loop Tutorial //
let pickup_truck = {"brand":"Ford", "model":"F-Series", "year":1984};
let even_numbers = [2,4,6,8,10];
// Without Loops
console.log(pickup_truck["brand"]);
console.log(pickup_truck.brand);
console.log(pickup_truck.model);
console.log(pickup_truck.year);
console.log(even_numbers[0]);
console.log(even_numbers[1]);
console.log(even_numbers[2]);
console.log(even_numbers[3]);
console.log(even_numbers[4]);
// For In Loop
for (let key in pickup_truck) {
    console.log(key + ": " + pickup_truck[key] + "\n");
}
for (let n in even_numbers) {
    console.log(n + ": " + even_numbers[n] + "\n");
}

JavaScript For In Code
OjamboShop.com Web IDE JavaScript For In Code

JavaScript For In Result
OjamboShop.com Web IDE Compiler Displaying JavaScript For In Result


Usage

You can use any IDE or text editor and the web browser to compile and execute JavaScript code. For this tutorial, the OjamboShop.com Learning JavaScript Course Web IDE was used to input and compile JavaScript code for the for in loop.

Open Source

JavaScript follows the ECMAScript standard and is licensed under the W3C Software License by web browser vendors and runtime environment vendors. This allows commercial use, modification, distribution, and allows making derivatives proprietary.

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Conclusion:

JavaScript makes it easy to use for in loop statements. Use a for in loop to iterate over the enumerable properties on an object.

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