how to use the isset function from the underscore library in javascript

The isset() function does not exist in JavaScript or the Underscore library. It is a PHP function used to determine if a variable is set and is not null.

However, in JavaScript, you can check if a variable is defined and has a value by using the typeof operator. To check whether a property or a variable is defined or not, you can use the hasOwnProperty() method.

Here is an example code snippet that checks if a variable is defined and not null using typeof:

index.tsx
if(typeof variableName !== 'undefined' && variableName !== null) {
  // variableName is defined and not null, do something with it
}
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Here is an example code snippet that checks if an object has a specific property using hasOwnProperty():

index.tsx
if(objectName.hasOwnProperty('propertyName')) {
  // objectName has the propertyName, do something with it
}
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Alternatively, you can use the _.isUndefined() and _.isNull() functions from the Underscore library to check for undefined and null values respectively. Here is an example code snippet:

index.tsx
if(!_.isUndefined(variableName) && !_.isNull(variableName)) {
  // variableName is defined and not null, do something with it
}
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