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For first scenario everything will work fine.
But it’s hard to beat the simplicity of color || (color = 'Pink');. Then it calls the method two times: first one passing two params and second one passing only one param. If a function changes an argument's value, it does not change the parameter's original value.
Default value is undefined, and true == undefined => false, so your default value will be false:) share | improve this answer | follow | answered Jan 24 at 13:12 Many programming languages support optional function arguments - ie. This feature can be used for any of the parameters in the function head, so you could set a default for the first parameter along with two other expected values that don’t have defaults: function getInfo ( … Much easier to maintain, and much easier to read. Now browseBlog() function getting called two times: first one is passing two params and second one pass only one param. This is where default parameters can help. logURL. In JavaScript haben Funktionsparameter standardmäßig den Default-Wert undefined. The optional chaining operator provides a way to simplify accessing values through connected objects when it's possible that a reference or function may be undefined or null. of parameters to a function and assign default value. You can set a default value for any argument - so if the argument is not present, the default value will be used. For example, consider an object obj which has a nested structure. JavaScript optional parameters allows Java developers to declare optional parameters. We can use this shortcut operator to manage optional parameters in JavaScript. In JavaScript, default function parameters allow you to initialize named parameters with default values if no values or undefinedare passed into the function. The parameters, in a function call, are the function's arguments. The following methods work if the parameter is never false. This method only allows the last arguments to be optional and you cannot make an optional first parameter, middle parameters are optional.In the preceding example, it declares a function browseBlog(blogURL, type) with two params blogURL and type. In JavaScript, function parameters default to undefined.
For first function call it displays alert as “In this article we discussed 3 ways to pass optional parameters in JavaScript. You can use any one of them as per suitability.
If 90% of the time you're calling a function using the same values for some parameters, you should look into making those parameters optional to …
The current JavaScript specification doesn't support function parameter default values right out the box, but as always there are ways.Where as in some other programming languages, parameter default values might be expressed like so:In JavaScript that’s not possible, the parameter needs to be treated like any old variable.The following methods work if the parameter is never false.This reminds the user that the parameter is needed:The following, friendlier example, gives it a default value of Pink:A really primitive example: if just anything is passed to the function, it’s possible to check the These all will fail if the parameter is needed to be If the parameter might also be false, check the type first with ECMAScript 6 (the new JavaScript language specification) supports default values out the box:This is currently only supported by FireFox. Earlier in this tutorial, you learned that functions can have parameters:Function parameters are the names listed in the function definition.Function arguments are the real values passed to (and received by) the function.