📰 Latest: HaasOnline Academy Is Back — Structured Education for Smarter Trade Bots
Account
Getting Started

Using Comments

Using Comments

Comments are non-executable text in your HaasScript code that explain what your code does and why it does it. While HaasScript ignores comments when executing your scripts, well-written comments are essential for creating maintainable, understandable trading strategies.

Why Comments Matter

  • Documentation: Explain complex logic and trading decisions
  • Memory aid: Remember why you wrote code a certain way weeks or months later
  • Collaboration: Help other traders understand your strategies
  • Debugging: Temporarily disable code without deleting it
  • Learning: Teach yourself and others how HaasScript works

HaasScript Comment Syntax

HaasScript supports two types of comments:

Single-Line Comments

Use -- for comments that span a single line:

-- This is a single-line comment
local rsiPeriod = Input("RSI Period", 14)  -- Comments can follow code

-- Blank space before comment improves readability
local rsi = RSI(ClosePrices(), rsiPeriod)

Multi-Line Comments

Use --[[ ]] for longer comments that span multiple lines:

--[[
This is a multi-line comment.
Use it for longer explanations
that don't fit on a single line.
]]

local rsi = RSI(ClosePrices(), 14)

You can also use this style to temporarily disable blocks of code:

--[[
local oldLogic = RSI(ClosePrices(), 14)
if oldLogic < 30 then
    DoLong("Old strategy")
end
--]]

-- New logic goes here
local newLogic = MACD(ClosePrices(), 12, 26, 9)

What to Comment

Comment why, not what. The code itself shows the what. Comments should explain the reasoning behind it.

Good Comments

-- Use 2x ATR for stop loss to accommodate normal volatility
local atr = ATR(HighPrices(), LowPrices(), ClosePrices(), 14)
local atrPercentage = (atr / ClosePrices()) * 100
StopLoss(atrPercentage * 2)

-- Only enter when both RSI and MACD confirm the signal
if rsi < 30 and macdSignal == SignalLong then
    DoLong("Dual indicator confirmation")
end

-- Tighter stop loss for scalping strategy
StopLoss(0.5)

Bad Comments

-- Define RSI period
local rsiPeriod = Input("RSI Period", 14)

-- Calculate RSI
local rsi = RSI(ClosePrices(), rsiPeriod)

-- Check if RSI is less than 30
if rsi < 30 then
    DoLong("Buy signal")
end

These comments just repeat what the code already says. They add no value.

Commenting Strategies

Script Headers

Always start your scripts with a header comment explaining the strategy:

-- ============================================
-- RSI Mean Reversion Strategy
--
-- Enters long when RSI is oversold (< 30)
-- Enters short when RSI is overbought (> 70)
-- Uses 2x ATR dynamic stop loss
--
-- Best for: Ranging markets with clear support/resistance
-- Risk: Medium
-- Timeframe: 1 hour or higher recommended
-- ============================================

local rsiPeriod = Input("RSI Period", 14)
local atrMultiplier = Input("ATR Multiplier", 2)

Section Dividers

Use comments to divide your script into logical sections:

-- ===== INPUT PARAMETERS =====
local rsiPeriod = Input("RSI Period", 14)
local buyLevel = Input("Buy Level", 30)

-- ===== INDICATOR CALCULATIONS =====
local rsi = RSI(ClosePrices(), rsiPeriod)
local macd = MACD(ClosePrices(), 12, 26, 9)

-- ===== ENTRY LOGIC =====
if rsi < buyLevel then
    DoLong("Entry signal")
end

-- ===== RISK MANAGEMENT =====
StopLoss(2.0)
TakeProfit(5.0)

Pro Tip - Foldable Sections:

Indent code under your section comments to create foldable sections in the editor. When you collapse a folded section, the comment remains visible as the label:

-- INPUT PARAMETERS
    local rsiPeriod = Input("RSI Period", 14)
    local buyLevel = Input("Buy Level", 30)
    local sellLevel = Input("Sell Level", 70)

-- INDICATOR CALCULATIONS
    local rsi = RSI(ClosePrices(), rsiPeriod)
    local macd = MACD(ClosePrices(), 12, 26, 9)
    local atr = ATR(HighPrices(), LowPrices(), ClosePrices(), 14)

-- ENTRY LOGIC
    if rsi < buyLevel then
        DoLong("Entry signal")
    end

When you fold these sections, you'll just see this:

-- INPUT PARAMETERS ...

-- INDICATOR CALCULATIONS ...

-- ENTRY LOGIC ...

This makes navigating large scripts much easier.

Explaining Complex Logic

Comment code that might not be immediately obvious:

-- Calculate position size based on account balance and risk percentage
-- Risk 2% of account per trade
local accountBalance = Balance()
local riskPercentage = 2
local riskAmount = (accountBalance / 100) * riskPercentage

-- Use ATR to calculate stop loss distance in price terms
local atr = ATR(HighPrices(), LowPrices(), ClosePrices(), 14)
local stopDistance = atr * 2

-- Calculate position size that respects risk amount
local positionSize = riskAmount / stopDistance

Documenting Input Parameters

Explain why you chose specific default values:

-- 14-period RSI is standard, widely used by traders
local rsiPeriod = Input("RSI Period", 14)

-- 30/70 levels reduce false signals compared to 20/80
local buyLevel = Input("Buy Level", 30)
local sellLevel = Input("Sell Level", 70)

-- 2x ATR accommodates normal market volatility
local atrMultiplier = Input("ATR Stop Loss Multiplier", 2)

Recording Strategy Performance

Keep a changelog of modifications and results:

-- ============================================
-- STRATEGY CHANGE LOG
-- ============================================
-- 2024-01-15: Initial version
-- 2024-01-20: Changed RSI period from 14 to 21 (fewer false signals)
-- 2024-02-01: Added MACD confirmation (improved win rate by 15%)
-- 2024-02-15: Adjusted stop loss from 1.5x to 2x ATR (reduced early exits)
-- ============================================

When NOT to Comment

Don't comment code that is self-explanatory:

-- Bad: These comments add no value
local rsi = RSI(ClosePrices(), 14)  -- Calculate RSI with period 14
local sma = SMA(ClosePrices(), 20)   -- Calculate SMA with period 20
local ema = EMA(ClosePrices(), 20)   -- Calculate EMA with period 20

-- Good: Code is clear without comments
local rsi = RSI(ClosePrices(), 14)
local sma = SMA(ClosePrices(), 20)
local ema = EMA(ClosePrices(), 20)

Don't comment outdated information:

-- Bad: Comment describes old code
-- Use RSI period of 21 for fewer signals
local rsi = RSI(ClosePrices(), 14)  -- This is now 14, not 21

-- Good: Either update the comment or remove it
local rsi = RSI(ClosePrices(), 14)

Commenting for Debugging

Use comments to debug by temporarily disabling code:

-- Original logic
if rsi < 30 then
    DoLong("RSI oversold")
end

-- Testing alternative logic
-- if rsi < 30 and macdSignal == SignalLong then
--     DoLong("RSI + MACD confirmation")
-- end

-- Keep both versions while testing, remove the old one when confirmed

Multi-Line Comment Tips

When using multi-line comments, maintain consistent formatting:

--[[
    Strategy: Moving Average Crossover
    Entry: When fast MA crosses above slow MA
    Exit: When fast MA crosses below slow MA
    Stop Loss: 2x ATR
    Take Profit: 1:2 risk-reward ratio

    Best for: Trending markets
    Avoid: Ranging or choppy markets
]]

local fastMA = EMA(ClosePrices(), 9)
local slowMA = EMA(ClosePrices(), 21)

Comment Density

Aim for the right balance—too few comments make code hard to understand, too many make it cluttered:

-- Too few: Hard to understand
local r = RSI(ClosePrices(), 14)
local m = MACD(ClosePrices(), 12, 26, 9)
if r < 30 and m == SignalLong then DoLong() end

-- Too many: Cluttered and redundant
-- Define the RSI period
local rsiPeriod = 14
-- Calculate RSI using ClosePrices and the period
local rsi = RSI(ClosePrices(), rsiPeriod)
-- Define the RSI buy level
local buyLevel = 30
-- Check if RSI is below buy level
if rsi < buyLevel then
    -- Execute a long position
    DoLong("Entry signal")
end

-- Just right: Clear and helpful
local rsiPeriod = Input("RSI Period", 14)
local rsi = RSI(ClosePrices(), rsiPeriod)
local buyLevel = Input("Buy Level", 30)

-- Enter when RSI is oversold
if rsi < buyLevel then
    DoLong("RSI oversold entry")
end

Commenting Best Practices

  1. Keep comments current: Update comments when you modify code
  2. Be concise: Say what you need to say, then stop
  3. Explain trading logic: Focus on the reasoning, not the syntax
  4. Document parameters: Explain why you chose specific values
  5. Date your changes: Add timestamps when making significant modifications
  6. Remove dead comments: Delete comments that no longer apply

Template Scripts

Create templates with helpful comments for reuse:

-- ============================================
-- TEMPLATE: Simple Indicator Strategy
-- ============================================
-- Strategy Name: [YOUR STRATEGY NAME]
-- Strategy Type: [Trend Following / Mean Reversion / Breakout]
-- Timeframe: [Best timeframes for this strategy]
-- Risk Level: [Low / Medium / High]
-- ============================================
-- CHANGE LOG
-- ============================================
-- YYYY-MM-DD: Initial creation
-- ============================================

-- ===== INPUT PARAMETERS =====
    -- Add user-configurable parameters here
    local indicatorPeriod = Input("Indicator Period", 14)
    local entryLevel = Input("Entry Level", 30)

-- ===== INDICATOR CALCULATIONS =====
    -- Calculate your indicators here
    local indicator = RSI(ClosePrices(), indicatorPeriod)

-- ===== ENTRY LOGIC =====
    -- Define your entry conditions
    if indicator < entryLevel then
        DoLong("Entry signal")
    end

-- ===== EXIT LOGIC =====
    -- Define your exit conditions
    if indicator > 70 then
        DoExitPosition("Exit signal")
    end

-- ===== RISK MANAGEMENT =====
    -- Set stop loss and take profit
    StopLoss(2.0)
    TakeProfit(5.0)

Review Your Comments

Before finalizing a script, review your comments:

  • Are they explaining why, not what?
  • Are they accurate and up to date?
  • Do they add value or just repeat the code?
  • Would another trader understand your strategy?
  • Are there any uncommented complex sections?

Good comments are the difference between a script that only you understand and one that others can use, modify, and improve.

← Previous Formatting
Back to HaasScript Fundamentals
Next → Editor Shortcuts