How to Use and Implement For Loops

Overview

A for loop is one of the most common programming constructs and is supported by most programming languages. It allows you to execute a block of code repeatedly while a specified condition remains true.

SurveyToGo supports both C# and JavaScript syntax, and both languages provide support for for loops. These loops are extremely useful when you need to perform the same action multiple times, such as processing answers, topics, iterations, or other survey elements.

This article covers:

1. Understanding the structure of a for loop.

2. Using for loops within SurveyToGo scripts.

Step 1: Understanding the Structure of a For Loop

A for loop consists of three components and a block of code that is executed repeatedly.

General Syntax

for ([Initial Expression]; [Condition]; [Increment Expression])
{
    // Action code
}

Components

Initial Expression

Executed only once when the loop begins. This is typically used to declare and initialize a counter variable.

Condition

Evaluated before each iteration. The loop continues to run as long as the condition remains true.

Increment Expression

Executed after each iteration. This is typically used to increase or decrease the counter variable.

Example

for (var i = 0; i < 10; i++)
{
    SetAnswer(CurrQues, i);
}

This loop executes 10 times.

How It Works

Initial Expression

var i = 0;

Creates a variable named i and sets its initial value to 0.

In C#, int i = 0; can be used instead of var i = 0;.

Condition

i < 10

The loop continues as long as the value of i is less than 10.

Increment Expression

i++

Increases the value of i by 1 after each iteration.

If the condition never becomes false, the loop will continue indefinitely, which can cause the survey to become unresponsive.

Action Code

The code inside the curly braces executes once during each iteration.

Step 2: Using For Loops in SurveyToGo

For loops can be used in most SurveyToGo scripting locations, including:

• Start Scripts

• End Scripts

• Survey Initialization Code

• Advanced Scripts

• Expression Questions

They cannot be used directly in:

• Entrance Rules

• Jump Rules

Example: Filtering Employees Based on Ratings

Assume you have:

• A grid question where each topic represents an employee.

• Answer choices representing ratings:

  1. Excellent

  2. Good

  3. Average

  4. Bad

  5. Horrible

The next question contains the same employee names as answers.

The requirement is to display only employees who received a rating of Bad or Horrible.

Start Script

Add the following code to the Start Script of the next question:

for (var i = 1; i <= GetTopicCount(CurrQues - 1); i++)
{
    if (AnswerChoice(CurrQues - 1, i) <= 3)
    {
        SetAnswerVisible(CurrQues, i, false);
    }
}

How It Works

The loop:

1. Iterates through all topics in the previous question.

2. Retrieves the selected rating for each topic.

3. Checks whether the rating is Average, Good, or Excellent (values 1–3).

4. Hides the corresponding answer in the current question.

As a result:

• Employees rated Excellent, Good, or Average are hidden.

• Only employees rated Bad or Horrible remain visible.

Summary

For loops are a powerful tool for automating repetitive tasks within SurveyToGo scripts. They are commonly used for:

• Processing answers or topics

• Applying filters

• Updating values

• Performing calculations

• Managing iterations

The employee-rating example above demonstrates only one possible use case. With for loops, you can implement a wide range of dynamic survey behaviors and advanced scripting logic.