Expressions - Amazon Lex

Expressions

You can add expressions strings to perform functions in Amazon Lex V2. This table shows the syntax and examples that can be used in SRGS expressions.

Expression type Syntax Example Supported?
Regular expression literal String literal containing valid regex special characters 
"^\d\.$"
 No
Function function functionName(parameters) { functionBody} 
var x = function calc() {
    return 10;
}
 No
Delete delete expression 
delete obj.property;
 No
Void void expression 
void (2 == '2');
 No
Typeof typeof expression 
typeof 42;
 No
Member index expression [ expressions ] 
var fruits = ["apple"];
fruits[0];
 Yes
Member dot expression . identifier 
out.value
 yes
Arguments expression (arguments) 
new Date('1994-10-11')
 Yes
Post increment expression++ 
var x=10; x++;
 Yes
Post decrement expression-- 
var x=10; x--;
 Yes
Pre increment ++expression 
var x=10; ++x;
 Yes
Pre decrement --expression 
var x=10; --x;
 Yes
Unary plus / Unary minus +expression / -expression 
+x / -x;
 Yes
Bit not ~ expression 
const a = 5;
console.log( ~a );
 Yes
Logical not ! expression 
!(a > 0 || b > 0)
 Yes
Multiplicative expression ('*' | '/' | '%') expression 
(x + y) * (a / b)
 Yes
Additive expression ('+' | '-') expression 
(a + b) - (a - (a + b))
 Yes
Bit shift expression ('<<' | '>>' | '>>>') expression 
(a >> b) >>> c
 Yes
Relative expression ('<' | '>' | '<=' | '>=') expression 
if (a > b) { ... }
 Yes
In expression in expression 
fruits[0] in otherFruits;
 Yes
Equality expression ('==' | '!=' | '===' | '!===') expression 
if (a == b) { ... }
 Yes
Bit and / xor / or expression ('&' | '^' | '|') expression 
a & b / a ^ b / a | b
 Yes
Logical and / or expression ('&&' | '||') expression 
if (a && (b ||c)) { ...}
 Yes
Ternary expression ? expression : expression 
a > b ? obj.prop : 0
 Yes
Assignment expression = expression 
out.value = "string";
 Yes
Assignment operator expression ('*=' | '/=' | '+=' | '-=' | '%=') expression 
a *= 10;
 Yes
Assignment bitwise operator expression ('<<=' | '>>=' | '>>>=' | '&=' | '^=' | '|=') expression 
a <<= 10;
 Yes
Identifier identifierSequence where identifierSequence is a sequence of valid characters 
fruits=[10, 20, 30];
 Yes
Null literal null 
x = null;
 Yes
Boolean literal true | false 
x = true;
 Yes
String literal 'string' / "string" 
a = 'hello',
b = "world";
 Yes
Decimal literal integer [.] digits [exponent] 
111.11 e+12
 Yes
Hex literal 0 (x | X)[0-9a-fA-F] 
0x123ABC
 Yes
Octal literal O [0-7] 
"O51"
 Yes
Array literal [ expression, ... ] 
v = [a, b, c];
 Yes
Object literal {property: value, ...} 
out = {value: 1, flag: false};
 Yes
Parenthesized ( expressions ) 
x + (x + y)
 Yes