With the Nullish Coalescing Operator, you can set a default value if value is null or undefined. const setVariable = localStorage.getItem('value ... ... <看更多>

In ES5, one would test parameter values in the body of the function and assign a value if they were undefined . In ES2015, a check in the function body is no ... ... <看更多>

JavaScript supported default parameters since ES2015 (or ES6) with the ... is the current year if you don't pass an argument or pass the undefined value. ... <看更多>

You know how, in JavaScript, we can set a value to a variable if one doesn't, like this: ... @JeffreyWay why not using null as default argument? ... <看更多>

However, we're looking up $newsItems[0]['image_url'] when calling default_value , and this is possibly not defined, and will raise an error/warning. If that's a ... ... <看更多>