Syntax, Parameter and Return Value
Syntax:
_.defaultTo(value, defaultValue)
Parameters:
-
value: The value to check for validity.
- defaultValue: The default value to return if the original value is invalid.
Return Value:
Returns the resolved value (either the original value if valid, or the default value).
Examples
Setting Default Value for Potentially Undefined Variable:
JavaScript
var _ = require('lodash');
var possiblyUndefined = undefined;
var safeValue = _.defaultTo(possiblyUndefined, 10);
console.log(safeValue);
You can also try this code with Online Javascript Compiler
Output:
10
Demonstrates using _.defaultTo() to set a default value when the original variable is undefined.
Handling Null Values in Data Processing:
JavaScript
var userAge = null;
var ageForProcessing = _.defaultTo(userAge, 18);
console.log(ageForProcessing);
You can also try this code with Online Javascript Compiler
Output:
18
Shows setting a default value for a variable that might be null.
Preventing NaN in Mathematical Operations:
JavaScript
function calculateDiscount(price, discount) {
discount = _.defaultTo(discount, 0);
return price - (price * discount);
}
console.log(calculateDiscount(100, NaN));
You can also try this code with Online Javascript Compiler
Output:
100
An example of using _.defaultTo() to avoid NaN results in calculations.
Using with Optional Object Properties:
JavaScript
var config = { timeout: null };
var timeoutValue = _.defaultTo(config.timeout, 1000);
console.log(timeoutValue);
You can also try this code with Online Javascript Compiler
Output:
1000
Demonstrates setting a default value for an optional property in an object.
Frequently Asked Questions
What types of values are considered invalid by _.defaultTo()?
_.defaultTo() considers NaN, null, and undefined as invalid values. Other falsy values like 0, '', and false are considered valid.
How does _.defaultTo() differ from logical OR (||) operator?
The logical OR operator (||) treats all falsy values (0, '', false, null, undefined, NaN) as invalid, whereas _.defaultTo() specifically checks for null, undefined, and NaN.
Is _.defaultTo() commonly used in real-world applications?
_.defaultTo() is particularly useful in applications where robustness and error handling are important, especially in dealing with external data or user inputs.
Conclusion
Lodash's _.defaultTo() method is an effective tool for ensuring that variables have valid values, providing a simple way to set default values in case of null, undefined, or NaN. It enhances code reliability by preventing errors related to invalid data.
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