It is called default function parameters . It allows formal parameters to be initialized with default values if no value or undefined is passed. NOTE: It wont ... ... <看更多>
In JavaScript, a parameter has a default value of undefined. It means that if you don't pass the arguments into the function, its parameters will have the ... ... <看更多>
Default parameters allow formal function parameters to be initialized with default values if no value (or undefined ) is supplied. In ES5, one would test ... ... <看更多>
When you don't pass the discount argument into the applyDiscount() function, the function uses a default value which is 0.05 . Similar to JavaScript ... ... <看更多>
Javascript is somewhat different in this regard as it's very loose about it type and method definitions, and it fills in a lot of the gaps ... ... <看更多>
