Learn Blockly - 10 Code Examples & CST Typing Practice Test

Blockly is an open-source visual block-based programming library developed by Google. It allows developers to embed a drag-and-drop block coding editor inside web or mobile apps, enabling users to create logic visually without writing text code.

View all 10 Blockly code examples →

Simple Blockly Program Blockly - Hello World Alert Blockly - Repeat Loop Example Blockly - Simple Math Operation Blockly - Variable Set/Change Blockly - If/Else Condition Blockly - Basic Function Blockly - Simple Animation Frame Blockly - Random Number Example Blockly - List Creation and Loop

Learn BLOCKLY with Real Code Examples

Updated Nov 25, 2025

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Code Sample Descriptions

Simple Blockly Program

document.addEventListener('keydown', function(e) {
    if (e.key === 'ArrowRight') sprite.x += 10;
    if (e.key === 'ArrowLeft') sprite.x -= 10;
});

A Blockly example where arrow-key input moves a sprite. Code shown is the JavaScript Blockly would generate.

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Blockly - Hello World Alert

window.alert('Hello World!');

Displays a browser alert using Blockly's 'text' and 'alert' blocks.

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Blockly - Repeat Loop Example

for (var i = 0; i < 10; i++) {
    console.log('Loop iteration: ' + i);
}

Repeats an action 10 times using a Blockly counting loop.

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Blockly - Simple Math Operation

var result = 5 + 7;
console.log(result);

Adds two numbers using Blockly math blocks.

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Blockly - Variable Set/Change

var score = 0;
score += 5;
console.log(score);

Demonstrates creating and updating a variable.

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Blockly - If/Else Condition

var x = 12;
if (x > 10) {
    console.log('Greater than 10');
} else {
    console.log('10 or less');
}

Uses condition blocks to compare a number.

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Blockly - Basic Function

function greet(name) {
    console.log('Hello ' + name);
}

greet('Alice');

A function created using Blockly's 'procedures' blocks.

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Blockly - Simple Animation Frame

function update() {
    sprite.x += 2;
    requestAnimationFrame(update);
}

update();

A loop that updates a position every animation frame.

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Blockly - Random Number Example

var n = Math.floor(Math.random() * 100);
console.log('Random:', n);

Uses Blockly math blocks to pick a random number.

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Blockly - List Creation and Loop

var items = ['apple','banana','orange'];
for (var i = 0; i < items.length; i++) {
    console.log(items[i]);
}

Creates a list and iterates through it using Blockly list/loop blocks.

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Frequently Asked Questions about Blockly

What is Blockly?

What are the primary use cases for Blockly?

Educational coding tools. Visual workflow builders. Robotics interfaces. No-code/low-code platforms. Logic editors for AI/automation apps

What are the strengths of Blockly?

Highly customizable and embeddable. Can generate real executable code. Supports complex logic visually. Great for education and no-code tools. Large community and Google backing

What are the limitations of Blockly?

Requires developer setup (not plug-and-play like Scratch). Must design your own blocks for advanced use. Generated code may need cleanup. Not ideal for very large programs. Performance may drop with huge workspaces

How can I practice Blockly typing speed?

CodeSpeedTest offers 10+ real Blockly code examples for typing practice. You can measure your WPM, track accuracy, and improve your coding speed with guided exercises.

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Code Sample Descriptions

Simple Blockly Program

document.addEventListener('keydown', function(e) {
    if (e.key === 'ArrowRight') sprite.x += 10;
    if (e.key === 'ArrowLeft') sprite.x -= 10;
});

A Blockly example where arrow-key input moves a sprite. Code shown is the JavaScript Blockly would generate.

Let’s Try →

Blockly - Hello World Alert

window.alert('Hello World!');

Displays a browser alert using Blockly's 'text' and 'alert' blocks.

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Blockly - Repeat Loop Example

for (var i = 0; i < 10; i++) {
    console.log('Loop iteration: ' + i);
}

Repeats an action 10 times using a Blockly counting loop.

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Blockly - Simple Math Operation

var result = 5 + 7;
console.log(result);

Adds two numbers using Blockly math blocks.

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Blockly - Variable Set/Change

var score = 0;
score += 5;
console.log(score);

Demonstrates creating and updating a variable.

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Blockly - If/Else Condition

var x = 12;
if (x > 10) {
    console.log('Greater than 10');
} else {
    console.log('10 or less');
}

Uses condition blocks to compare a number.

Let’s Try →

Blockly - Basic Function

function greet(name) {
    console.log('Hello ' + name);
}

greet('Alice');

A function created using Blockly's 'procedures' blocks.

Let’s Try →

Blockly - Simple Animation Frame

function update() {
    sprite.x += 2;
    requestAnimationFrame(update);
}

update();

A loop that updates a position every animation frame.

Let’s Try →

Blockly - Random Number Example

var n = Math.floor(Math.random() * 100);
console.log('Random:', n);

Uses Blockly math blocks to pick a random number.

Let’s Try →

Blockly - List Creation and Loop

var items = ['apple','banana','orange'];
for (var i = 0; i < items.length; i++) {
    console.log(items[i]);
}

Creates a list and iterates through it using Blockly list/loop blocks.

Let’s Try →

Frequently Asked Questions about Blockly

What is Blockly?

What are the primary use cases for Blockly?

Educational coding tools. Visual workflow builders. Robotics interfaces. No-code/low-code platforms. Logic editors for AI/automation apps

What are the strengths of Blockly?

Highly customizable and embeddable. Can generate real executable code. Supports complex logic visually. Great for education and no-code tools. Large community and Google backing

What are the limitations of Blockly?

How can I practice Blockly typing speed?

CodeSpeedTest offers 10+ real Blockly code examples for typing practice. You can measure your WPM, track accuracy, and improve your coding speed with guided exercises.