Use of javascript function inside if statement

Question

Can someone explain how the following if statement works. Inside the if statement there is a test for function addFieldToText, and its arguments. After this line the script jumps into the addFieldToText function

 if(!addFieldToText(refworksFieldMappingEntry.enterpriseCode, refworksFieldMappingEntry))

Is it basically saying if this function has not been called yet, then call it? Hope this makes sense.

nicholaswmin · Accepted Answer · 2019-01-12 15:27:39Z

1

As soon as that if statement is encountered, it:

Calls the addFieldToText function passing refworksFieldMappingEntry.enterpriseCode, refworksFieldMappingEntry as arguments.
If addFieldToText returns false based on those arguments value, then the if statement is executed.

If the addFieldToText was not prefixed with ! (NOT operator) then addFieldToText would have to return a truthy value for the if statement to execute.

Here's a simplified example:

const isNumberDivisibleBy2 = (num) => {
  return num % 2 === 0
}

if (!isNumberDivisibleBy2(9)) {
  console.log('number is NOT divisible by 2')
} else {
  console.log('number is divisible by 2')
}

edited Jan 12, 2019 at 15:27

answered Jan 12, 2019 at 15:22

nicholaswmin

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