Syntax Guide

PineTS Syntax Guide

This guide explains how to write PineTS code that is equivalent to Pine Script. PineTS is designed to be written in JavaScript/TypeScript but behaves like Pine Script's runtime execution model.

Variable Declarations

PineTS distinguishes between let and var declarations to mimic Pine Script's behavior. This is a critical difference from standard JavaScript.

let vs var

⚠️ Important for JS Developers: In PineTS, var does not behave like standard JavaScript var. It adopts Pine Script's var semantics (persistent state). If you need standard JS function-scoped variables that reset every time, use let.

Example: State Persistence

Pine Script:

// 'sum' retains its value across bars
var float sum = 0.0
sum := sum + close

PineTS:

// 'sum' retains its value across bars
var sum = 0.0;
sum = sum + close;

Loops

PineTS supports standard JavaScript loops, which map to Pine Script's loops.

Example: For Loop

Pine Script:

float sum = 0.0
for i = 0 to 9
    sum := sum + close[i]

PineTS:

let sum = 0.0;
for (let i = 0; i < 10; i++) {
    sum += close[i];
}

Control Structures

Switch Statement

PineTS supports the JavaScript switch statement, which is equivalent to Pine Script's switch.

Pine Script:

switch type
    "ema" => ta.ema(close, len)
    "sma" => ta.sma(close, len)
    => ta.rma(close, len)

PineTS:

switch (type) {
    case 'ema':
        return ta.ema(close, len);
    case 'sma':
        return ta.sma(close, len);
    default:
        return ta.rma(close, len);
}

Functions

User-defined functions in PineTS are written as standard JavaScript functions.

Pine Script:

f_ma(source, length) =>
    ta.sma(source, length)

PineTS:

function f_ma(source, length) {
    return ta.sma(source, length);
}

Tuples and Multiple Return Values

Pine Script allows functions to return multiple values (tuples). PineTS handles this using array destructuring.

Pine Script:

[macdLine, signalLine, histLine] = ta.macd(close, 12, 26, 9)

PineTS:

const [macdLine, signalLine, histLine] = ta.macd(close, 12, 26, 9);

Series and History Access

Accessing historical values is done using the [] operator in Pine Script. In PineTS, array access syntax is supported and transpiled to safe series access.

PineTS:

// Calculate momentum
let mom = close - close[10];

Conditional Logic

PineTS supports standard JavaScript control flow, which maps to Pine Script's execution model.

Example: Trend Direction

Pine Script:

if close > open
    direction := 1
else
    direction := -1

PineTS:

if (close > open) {
    direction = 1;
} else {
    direction = -1;
}

Always brace your if / for / while bodies

The rule: In the JS callback form, every control-flow body must be wrapped in { ... } — even single statements.

JavaScript itself allows brace-less single-statement bodies (if (cond) stmt;). PineTS does not. If the body contains any Pine namespace call (strategy.entry, ta.sma, plot, line.new, label.new, ...), brace-less bodies produce silent bugs.

Why. The PineTS transpiler rewrites Pine-style calls into a "compute first, use second" form — strategy.entry('e', strategy.long, 1) becomes a few const p_N = strategy.param(...) declarations followed by const temp_N = strategy.entry(...). Those pN / temp_N declarations are hoisted: they must be emitted before the statement that needs them, and they must land in the smallest enclosing BlockStatement so that they execute only when that block does.

The transpiler's hoisting walker only has a hook for BlockStatement. When the body of an if / for / while is a plain single statement (brace-less), there is no inner block to catch the hoisted declarations — they fall through to the next enclosing block (typically the parent function body) and end up executing on every bar, ignoring the condition or the loop counter.

Pine source isn't affected because Pine's indentation-scoped bodies are always emitted as a BlockStatement by the Pine → JS codegen, regardless of how many statements they contain.

Example 1 — if body

// ❌ WRONG — strategy.entry() fires on EVERY bar.
if ($.idx === 1) strategy.entry('e', strategy.long, 1);

// ✅ CORRECT
if ($.idx === 1) { strategy.entry('e', strategy.long, 1); }

What the transpiler emits in the wrong case:

const temp_3 = strategy.entry(p2, temp_2, p3);   // ← runs every bar
if ($.idx === 1) temp_3;                          // ← reads value, no-op

Example 2 — for body

// ❌ WRONG — strategy.order() runs ONCE, not 3 times.
for (let k = 0; k < 3; k++) strategy.order('o' + k, strategy.long, 1);

// ✅ CORRECT
for (let k = 0; k < 3; k++) { strategy.order('o' + k, strategy.long, 1); }

What the transpiler emits in the wrong case:

const p2 = strategy.param('o' + k, ...);          // ← `k` not in scope yet — ReferenceError
const temp_3 = strategy.order(p2, temp_2, p3);    // ← runs once, before the loop
for (let k = 0; k < 3; k++) temp_3;               // ← loop reads the same temp

The same applies to while bodies and brace-less else branches.

If a single-statement body contains no Pine namespace call (pure JS arithmetic, plain variable assignment, a console.log, etc.), no hoisting happens and brace-less is harmless. The safe default is to always use braces.

Built-in Variables

PineTS exposes Pine Script's built-in variables through the context object, but usually, you destructure them for easier access.

PineTS Setup:

const { close, high, low } = context.data;
const { bar_index } = context.pine;

Functions and Namespaces

PineTS organizes built-in functions into namespaces similar to Pine Script v5.

PineTS Setup:

const { ta, math } = context.pine;
// Usage
const sma = ta.sma(close, 14);

Full Example: Parabolic SAR

This example demonstrates var for state, if/else logic, and history access.

Pine Script:

pine_sar(start, inc, max) =>
    var float result = na
    var float maxMin = na
    var float acceleration = na
    var bool isBelow = false
    bool isFirstTrendBar = false

    if bar_index == 1
        if close > close[1]
            isBelow := true
            maxMin := high
            result := low[1]
        else
            isBelow := false
            maxMin := low
            result := high[1]
        isFirstTrendBar := true
        acceleration := start

    // ... logic continues ...
    result

PineTS:

function pine_sar(start, inc, max) {
    // Use 'var' for state variables (persistent)
    var result = na;
    var maxMin = na;
    var acceleration = na;
    var isBelow = false;

    // Use 'let' for temporary variables (reset every bar)
    let isFirstTrendBar = false;

    if (bar_index == 1) {
        if (close > close[1]) {
            isBelow = true;
            maxMin = high;
            result = low[1];
        } else {
            isBelow = false;
            maxMin = low;
            result = high[1];
        }
        isFirstTrendBar = true;
        acceleration = start;
    }

    // ... logic continues ...

    return result;
}