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LiveCodes supports WebAssembly through WAT (WebAssembly Text Format), allowing you to write and execute low-level code directly in the browser.

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Configuration

Language Name: wat
File Extensions: .wat, .wast, .webassembly, .wasm
Editor: Script editor
Compiler: wabt.js (WebAssembly Binary Toolkit)
Output: Binary WebAssembly module

​
WebAssembly Text Format (WAT)

WAT is the human-readable text format for WebAssembly:

​
Basic Module

(module
  ;; Import console.log from JavaScript
  (import "env" "log" (func $log (param i32)))
  
  ;; Export a function
  (func $add (param $a i32) (param $b i32) (result i32)
    local.get $a
    local.get $b
    i32.add
  )
  (export "add" (func $add))
  
  ;; Function that calls imported function
  (func $printSum (param $a i32) (param $b i32)
    local.get $a
    local.get $b
    i32.add
    call $log
  )
  (export "printSum" (func $printSum))
)

​
Functions

(module
  ;; Simple function
  (func $double (param $x i32) (result i32)
    local.get $x
    i32.const 2
    i32.mul
  )
  (export "double" (func $double))
  
  ;; Function with local variables
  (func $factorial (param $n i32) (result i32)
    (local $result i32)
    (local $i i32)
    
    ;; Initialize result to 1
    i32.const 1
    local.set $result
    
    ;; Initialize counter to 1
    i32.const 1
    local.set $i
    
    ;; Loop
    (block $break
      (loop $continue
        ;; Break if i > n
        local.get $i
        local.get $n
        i32.gt_s
        br_if $break
        
        ;; result *= i
        local.get $result
        local.get $i
        i32.mul
        local.set $result
        
        ;; i++
        local.get $i
        i32.const 1
        i32.add
        local.set $i
        
        ;; Continue loop
        br $continue
      )
    )
    
    local.get $result
  )
  (export "factorial" (func $factorial))
)

​
Control Flow

(module
  ;; If-else
  (func $max (param $a i32) (param $b i32) (result i32)
    local.get $a
    local.get $b
    i32.gt_s
    (if (result i32)
      (then
        local.get $a
      )
      (else
        local.get $b
      )
    )
  )
  (export "max" (func $max))
  
  ;; Loop
  (func $sum (param $n i32) (result i32)
    (local $result i32)
    (local $i i32)
    
    i32.const 0
    local.set $result
    
    i32.const 0
    local.set $i
    
    (block $break
      (loop $continue
        local.get $i
        local.get $n
        i32.ge_s
        br_if $break
        
        local.get $result
        local.get $i
        i32.add
        local.set $result
        
        local.get $i
        i32.const 1
        i32.add
        local.set $i
        
        br $continue
      )
    )
    
    local.get $result
  )
  (export "sum" (func $sum))
)

​
Memory

(module
  ;; Define memory (1 page = 64KB)
  (memory 1)
  (export "memory" (memory 0))
  
  ;; Store and load
  (func $storeValue (param $offset i32) (param $value i32)
    local.get $offset
    local.get $value
    i32.store
  )
  (export "storeValue" (func $storeValue))
  
  (func $loadValue (param $offset i32) (result i32)
    local.get $offset
    i32.load
  )
  (export "loadValue" (func $loadValue))
  
  ;; Initialize memory with data
  (data (i32.const 0) "Hello, WASM!")
  
  ;; Get string length
  (func $getStringLength (result i32)
    i32.const 12  ;; Length of "Hello, WASM!"
  )
  (export "getStringLength" (func $getStringLength))
)

​
Tables and Indirect Calls

(module
  ;; Define a table for function references
  (table 3 funcref)
  
  (func $add (param i32 i32) (result i32)
    local.get 0
    local.get 1
    i32.add
  )
  
  (func $sub (param i32 i32) (result i32)
    local.get 0
    local.get 1
    i32.sub
  )
  
  (func $mul (param i32 i32) (result i32)
    local.get 0
    local.get 1
    i32.mul
  )
  
  ;; Initialize table
  (elem (i32.const 0) $add $sub $mul)
  
  ;; Call function by index
  (func $callByIndex (param $index i32) (param $a i32) (param $b i32) (result i32)
    local.get $a
    local.get $b
    local.get $index
    call_indirect (param i32 i32) (result i32)
  )
  (export "callByIndex" (func $callByIndex))
)

​
Data Types

​
Numeric Types

(module
  ;; i32 (32-bit integer)
  (func $i32_demo (result i32)
    i32.const 42
  )
  
  ;; i64 (64-bit integer)
  (func $i64_demo (result i64)
    i64.const 9007199254740991
  )
  
  ;; f32 (32-bit float)
  (func $f32_demo (result f32)
    f32.const 3.14159
  )
  
  ;; f64 (64-bit float)
  (func $f64_demo (result f64)
    f64.const 2.718281828459045
  )
  
  (export "i32" (func $i32_demo))
  (export "i64" (func $i64_demo))
  (export "f32" (func $f32_demo))
  (export "f64" (func $f64_demo))
)

​
Using WASM in JavaScript

After compiling WAT to WASM, use it in JavaScript: 
// The compiled WASM module is automatically loaded
// Access exported functions:

// Simple function call
const result = add(5, 3);
console.log('5 + 3 =', result); // 8

// Factorial
const fact = factorial(5);
console.log('5! =', fact); // 120

// Memory operations
storeValue(0, 42);
const value = loadValue(0);
console.log('Stored value:', value); // 42

// Read string from memory
const memory = new Uint8Array(wasmMemory.buffer);
const decoder = new TextDecoder();
const str = decoder.decode(memory.slice(0, getStringLength()));
console.log('String:', str); // "Hello, WASM!"

​
Example Projects

​
Math Functions

(module
  ;; Fibonacci
  (func $fibonacci (param $n i32) (result i32)
    local.get $n
    i32.const 2
    i32.lt_s
    (if (result i32)
      (then
        local.get $n
      )
      (else
        (local $a i32)
        (local $b i32)
        (local $i i32)
        
        i32.const 0
        local.set $a
        
        i32.const 1
        local.set $b
        
        i32.const 2
        local.set $i
        
        (block $break
          (loop $continue
            local.get $i
            local.get $n
            i32.gt_s
            br_if $break
            
            (local $temp i32)
            local.get $a
            local.get $b
            i32.add
            local.set $temp
            
            local.get $b
            local.set $a
            
            local.get $temp
            local.set $b
            
            local.get $i
            i32.const 1
            i32.add
            local.set $i
            
            br $continue
          )
        )
        
        local.get $b
      )
    )
  )
  (export "fibonacci" (func $fibonacci))
  
  ;; Power function
  (func $pow (param $base f64) (param $exp i32) (result f64)
    (local $result f64)
    (local $i i32)
    
    f64.const 1.0
    local.set $result
    
    i32.const 0
    local.set $i
    
    (block $break
      (loop $continue
        local.get $i
        local.get $exp
        i32.ge_s
        br_if $break
        
        local.get $result
        local.get $base
        f64.mul
        local.set $result
        
        local.get $i
        i32.const 1
        i32.add
        local.set $i
        
        br $continue
      )
    )
    
    local.get $result
  )
  (export "pow" (func $pow))
)

​
Array Operations

(module
  (memory 1)
  (export "memory" (memory 0))
  
  ;; Sum array
  (func $sumArray (param $offset i32) (param $length i32) (result i32)
    (local $sum i32)
    (local $i i32)
    
    i32.const 0
    local.set $sum
    
    i32.const 0
    local.set $i
    
    (block $break
      (loop $continue
        local.get $i
        local.get $length
        i32.ge_s
        br_if $break
        
        local.get $sum
        local.get $offset
        local.get $i
        i32.const 4
        i32.mul
        i32.add
        i32.load
        i32.add
        local.set $sum
        
        local.get $i
        i32.const 1
        i32.add
        local.set $i
        
        br $continue
      )
    )
    
    local.get $sum
  )
  (export "sumArray" (func $sumArray))
  
  ;; Find max in array
  (func $maxArray (param $offset i32) (param $length i32) (result i32)
    (local $max i32)
    (local $i i32)
    (local $current i32)
    
    local.get $offset
    i32.load
    local.set $max
    
    i32.const 1
    local.set $i
    
    (block $break
      (loop $continue
        local.get $i
        local.get $length
        i32.ge_s
        br_if $break
        
        local.get $offset
        local.get $i
        i32.const 4
        i32.mul
        i32.add
        i32.load
        local.set $current
        
        local.get $current
        local.get $max
        i32.gt_s
        (if
          (then
            local.get $current
            local.set $max
          )
        )
        
        local.get $i
        i32.const 1
        i32.add
        local.set $i
        
        br $continue
      )
    )
    
    local.get $max
  )
  (export "maxArray" (func $maxArray))
)

​
Code Formatting

Automatic formatting with wast-refmt: 
;; Before formatting
(module(func $add(param i32)(param i32)(result i32)local.get 0 local.get 1 i32.add)(export"add"(func $add)))

;; After formatting (Ctrl+Shift+F)
(module
  (func $add (param i32) (param i32) (result i32)
    local.get 0
    local.get 1
    i32.add
  )
  (export "add" (func $add))
)

​
Best Practices

Name parameters and locals for clarity:
;; Good
(func $add (param $a i32) (param $b i32) (result i32)
  local.get $a
  local.get $b
  i32.add
)

;; Less clear
(func $add (param i32) (param i32) (result i32)
  local.get 0
  local.get 1
  i32.add
)
Check bounds before memory operations:
(func $safeLoad (param $offset i32) (result i32)
  local.get $offset
  i32.const 1024
  i32.lt_u
  (if (result i32)
    (then
      local.get $offset
      i32.load
    )
    (else
      i32.const 0
    )
  )
)

​
Limitations

No Direct DOM Access: WebAssembly cannot directly manipulate the DOM. Use JavaScript interop.
WAT is the text format. For production, compile to binary .wasm for smaller size and faster loading.

AssemblyScript

TypeScript-like syntax to WASM

Go (WASM)

Compile Go to WebAssembly

Rust

Rust to WebAssembly

C/C++

Compile C/C++ to WASM

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