Forms: Autofill Fields

In DSPTCH forms, you can automatically populate fields using expressions and built-in functions. These expressions allow you to reference other answers, perform calculations, and dynamically generate values in real time as the user completes the form. For example, you can combine multiple fields into a single value, evaluate conditions, or derive outputs using functions like iif , sum , or age . This guide provides examples and explains how to use expressions to auto-fill fields within your forms.

Expressions require compatible data types to function correctly. For example, when using sum() to combine values from multiple responses, both the input fields and the target field must use a numeric data type.

To see all possible expressions, view the documentation below:

In the documentation, when you see a value in brackets {} , that refers to the Question name.

For example, if you wanted to sum the values in question1 and question2 , in Default value expression you would put sum({question1}, {question2})

`iif`

Definition: iif(condition: expression, valueIfTrue: any, valueIfFalse: any): any

Returns the valueIfTrue value if the condition is truthy or the valueIfFalse value if the condition is falsy.

Example: "expression": "iif({question1} + {question2} > 20, 'High', 'Low')"

`isContainerReady`

Definition: isContainerReady(nameOfPanelOrPage: string): boolean

Returns true if all questions in a given panel or page have valid input; otherwise, returns false . An empty question value is considered valid if neither validators nor required status is defined for it.

Example: "expression": "isContainerReady('page1')"

`isDisplayMode`

Definition: isDisplayMode(): boolean

Returns true if the survey is in display or preview mode.

Example: "expression": "isDisplayMode()"

`age`

Definition: age(birthdate: any): number

Returns age according to a given birthdate. The date argument (which is typically taken from a question) should be defined as a valid JavaScript Date.

Example: "expression": "age({birthdate})"

`currentDate`

Definition: currentDate(): Date

Returns the current date and time.

Example: "expression": "currentDate()"

`today`

Definition: today(daysToAdd?: number): Date

Returns the current date or a date shifted from the current by a given number of days. For example, today() returns the current date, 0 hours, 0 minutes, 0 seconds; today(-1) returns yesterday's date, same time; today(1) returns tomorrow's date, same time.

Examples:

"expression": "today()"
"expression": "today(2)"

`year`

Definition: year(date?: Date): number

Returns the year of a given date.

Example: "expression": "year({birthdate})"

`month`

Definition: month(date?: Date): number

Returns the month of a given date as a value from 1 (January) to 12 (December).

Example: "expression": "month({birthdate})"

`day`

Definition: day(date?: Date): number

Returns the day of the month for a given date as a value from 1 to 31.

Example: "expression": "day({birthdate})"

`weekday`

Definition: weekday(date?: Date): number

Returns the day of the week for a given date as a value from 0 (Sunday) to 6 (Saturday).

Example: "expression": "weekday({birthdate})"

`getDate`

Definition: getDate(question: expression): Date

Returns a Date value converted from a given question's value.

Example: "expression": "getDate({birthdate})"

`dateAdd`

Adds or subtracts a specified number of days (default), hours, minutes, seconds, months, or years to or from a date value.

Example: "expression": "dateAdd({startDate}, 14, "days")"

`dateDiff`

Returns a difference between two given dates in days (default), hours, minutes, seconds, months, or years.

Example: "expression": "dateDiff({birthdate}, today(), "months")"

`sum`

Definition: sum(param1: number, param2: number, ...): number

Returns the sum of passed numbers.

Example: "expression": "sum({total1}, {total2})"

`max`

Definition: max(param1: number, param2: number, ...): number

Returns the maximum of passed numbers.

Example: "expression": "max({total1}, {total2})"

`min`

Definition: min(param1: number, param2: number, ...): number

Returns the minimum of passed numbers.

Example: "expression": "min({total1}, {total2})"

`avg`

Definition: avg(param1: number, param2: number, ...): number

Returns the average of passed numbers.

Example: "expression": "avg({total1}, {total2}, {total3})"

`round`

Definition: round(num: number, precision?: number): number

Rounds the given number to the specified number of decimal places. If the precision parameter is omitted, the given number is rounded to the nearest integer.

Examples:

"expression": "round({numericQuestion}, 2)" // Rounds the value of `numericQuestion` to two decimal places
"expression": "round(0.5)" // 1
"expression": "round(-0.5)" // -1
"expression": "round(1.005, 2)" // 1.01
"expression": "round(2.175, 2)" // 2.18
"expression": "round(-1.005, 2)" // -1.01
"expression": "round(-2.175, 2)" // -2.18

`trunc`

Definition: trunc(num: number, precision?: number): number

Truncates the given number to the specified number of decimal places. If the precision parameter is omitted, only the integer part is returned. Trailing zeroes in the decimal part are removed after truncation.

Examples:

"expression": "trunc({numericQuestion}, 2)" // Truncates the value of `numericQuestion` to two decimal places
"expression": "trunc(0.5)" // 0
"expression": "trunc(-0.5)" // 0
"expression": "trunc(1.005, 2)" // 1
"expression": "trunc(2.175, 1)" // 2.1
"expression": "trunc(-1.005, 2)" // -1
"expression": "trunc(-2.175, 1)" // -2.1

`sumInArray`

Definition: sumInArray(question: expression, dataFieldName: string, filter?: expression): number

Returns the sum of numbers taken from a specified data field. This data field is searched in an array that contains a user response to a Multi-Select Matrix, Dynamic Matrix, or Dynamic Panel question. The optional filter parameter defines a rule according to which values are included in the calculation.

The following code sums up values from a "total" matrix column but includes only the rows where a "categoryId" column equals 1:

Example: "expression": "sumInArray({matrixdynamic}, 'total', {categoryId} = 1)"

`maxInArray`

Definition: maxInArray(question: expression, dataFieldName: string, filter?: expression): number

Returns the maximum of numbers taken from a specified data field. This data field is searched in an array that contains a user response to a Multi-Select Matrix, Dynamic Matrix, or Dynamic Panel question. The optional filter parameter defines a rule according to which values are included in the calculation.

The following code finds a maximum value within a "quantity" matrix column, but the value should be under 100:

Example: "expression": "maxInArray({matrixdynamic}, 'quantity', {quantity} < 100)"

`minInArray`

Definition: minInArray(question: expression, dataFieldName: string, filter?: expression): number

Returns the minimum of numbers taken from a specified data field. This data field is searched in an array that contains a user response to a Multi-Select Matrix, Dynamic Matrix, or Dynamic Panel question. The optional filter parameter defines a rule according to which values are included in the calculation.

The following code finds a minimum value within a "quantity" matrix column but searches for it only in the rows where a "categoryId" column equals 1 and the values are positive:

Example: "expression": "minInArray({matrixdynamic}, 'quantity', {quantity} > 0 and {categoryId} = 1)"

`avgInArray`

Definition: avgInArray(question: expression, dataFieldName: string, filter?: expression): number

Returns the average of numbers taken from a specified data field. This data field is searched in an array that contains a user response to a Multi-Select Matrix, Dynamic Matrix, or Dynamic Panel question. The optional filter parameter defines a rule according to which values are included in the calculation.

The following code finds an average of values within a "quantity" matrix column, excluding zeroes:

Example: "expression": "avgInArray({matrixdynamic}, 'quantity', {quantity} > 0)"

`countInArray`

Definition: countInArray(question: expression, dataFieldName: string, filter?: expression): number

Returns the total number of array items in which a specified data field has a value other than null or undefined . This data field is searched in an array that contains a user response to a Multi-Select Matrix, Dynamic Matrix, or Dynamic Panel question.

The following code finds the total number of matrix rows with a "quantity" column value greater than zero but includes only the rows where a "categoryId" column equals 1.:

Example: "expression": "countInArray({matrixdynamic}, 'quantity', {quantity} > 0 and {categoryId} = 1)"

`displayValue`

Definition: displayValue(questionName: string, value?: any): any

Returns a question's display text. Supports questions nested within panels or matrices.

The second parameter allows you to get a display text associated with a specific value rather than with the current question value. For instance, the following expression references a display text that corresponds to value 5 in a Dropdown question. If you don't pass the second parameter, the displayValue function returns a display text for the currently selected question value.

Example: "expression": "displayValue('my-dropdown-question', 5)"

When using the displayValue function within a setValueExpression , specify the setValueIf expression as well. This requirement stems from the fact that the setValueExpression is reevaluated only when setValueIf is true or once the value of a referenced question is changed. Although you do pass a question name to the displayValue function, this name is only used to access the question within JavaScript code and doesn't directly reference it. To trigger the reevaluation in this case, define the setValueIf expression as follows:

"setValueExpression": "displayValue('my-dropdown-question')",
"setValueIf": "{my-dropdown-question} notempty"