Return

All Arcade expressions must return a value. The permissible data types returned from an Arcade expression are defined by the profile. There are two types of return statements: explicit returns and implicit returns.

Explicit returns

An explicit return is always preceded with the return keyword. This can be used for single-line expressions...

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return "Hello world";

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return ( ($feature.POP_2010 - $feature.POP_2000) / $feature.POP_2000) * 100;

...and multi-line expressions.

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var total = 5 + 10;
return total;

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var myArray = [10,20,30,40,50,60,70];
var total = 0;
for(var k in myArray){
  total += myArray[k];
}
return total;

It can also be used when defining functions.

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function calculateRatio(values, index){
  var value = values[index];
  return value / Sum(values);
}

Implicit returns

An implicit return returns the last executable statement of an expression. This is true regardless of an expression's length.

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5 + 10;
// returns 15

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($feature.POP_2010 / $feature.POP_2000) * 100;

Although the return keyword is not used in these multi-line expressions, the value of total is still returned.

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var total = 5 + 10;
total;
// returns 15

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var myArray = [10,20,30,40,50,60,70];
var total = 0;
for(var k in myArray){
  total += myArray[k];
}
total;
// returns 280

User-defined functions can also be written with an implicit return.

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function calculateRatio(values, index){
  var value = values[index];
  // the value computed in the final statement is returned by the function
  value / Sum(values);
}

Guidelines

Expressions with explicit returns benefit from providing clarity to anyone reading it. When multi-line expressions lack an explicit return, it can be easily interpreted as incomplete or unfinished. The following are suggested guidelines when authoring expressions.

• Always use explicit returns when defining custom functions.
• Use implicit returns in single-line expressions.
• Always use explicit returns in multi-line expressions.