Basic Expression in Adobe After Effects: A Step-by-Step Guide

Expressions in Adobe After Effects are like short codes that allow you to automate animations and create complex motion graphics easily—without keyframes. They save time and make animations dynamic and responsive. Let’s break down the basics of using expressions for beginners.

---

✅ What Are Expressions?

Expressions are written in JavaScript and are used to control property values such as position, scale, rotation, and opacity. Instead of setting multiple keyframes, an expression can create automatic animations or link one property to another.

---

🛠 How to Add an Expression

1. Select a Layer
   Click on the layer where you want to apply the expression.

2. Show the Property
   Press P for Position, R for Rotation, S for Scale, etc.

3. Add Expression
   Hold Alt (Windows) or Option (Mac) and click the stopwatch icon next to the property.

4. Type Your Expression
   A text box appears. Enter your expression or use the pick whip to link.

---

🧪 Most Common Basic Expressions

🔁 Loop Expression

Automatically loops an animation.

loopOut("cycle");

Use this on position or opacity to loop animations endlessly.

---

🔄 Wiggle Expression

Creates random motion (great for camera shake or flickering effects).

wiggle(2, 20);

• 2 = Frequency (times per second)

• 20 = Amplitude (range of movement)

---

🔗 Pick Whip Expression

Link a property to another layer's property.

Example:

thisComp.layer("Null 1").transform.rotation;

This makes your layer rotate based on "Null 1"’s rotation.

---

🎯 Time-Based Expression

Create continuous movement over time.

time * 100;

This expression makes position or rotation change continuously over time.

---

💡 Expression Tips

• Use comments in complex expressions: // This is a comment

• Disable expression temporarily: uncheck the stopwatch.

• Error Red Line = There's a mistake in the expression (usually typos).

---

📌 Use Cases

• Looping animations without repeating keyframes.

• Adding random camera movement.

• Connecting object properties for cleaner workflows.

• Auto-rotating objects or moving based on time.

---

🧰 Best Practice

• Use Null objects for complex linking.

• Always name layers properly to avoid confusion when using expressions.

• Pre-compose layers when needed for neatness and better performance.

---

🔚 Conclusion

Expressions can look scary at first, but they’re incredibly powerful once you understand the basics. Start with simple ones like wiggle() or loopOut() and explore deeper over time.

🧠 “Expressions are like a smart assistant inside After Effects — once you know the language, the possibilities are endless.”