I'm using the library handsontable and I'd like to get my application running in IE8-IE9 (even though it's not IE < 10 compatible...). When my code use the minify version I get an error in the JS console : "';' expected".
Here is the code.
{
get DEFAULT_WIDTH() {
return 50;
}
}
I just don't know this syntax. What does get DEFAULT_WIDTH() do?
The
getsyntax binds an object property to a function that will be called when that property is looked up.https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/get
The more general and exhausting explanation can be found here:
Basically, it allows you to define what happens when a certain object property is read by code. In an analogous fashion, you can also define what should happen when code writes to that property with a set definition. In both cases you overwrite the standard behaviour for that object property.
This is all part of ECMAScript 5.1, and thus, not available in IE < 9.
In your example code, you can see that whenever the property DEFAULT_WIDTH is read, a constant value will be returned. I guess the intention of this is to make sure DEFAULT_WIDTH cannot be redefined as some other value (which it in fact can, but reading it will still return 50).
Defining a getter on existing objects using defineProperty
To append a getter to an existing object later at any time, use
Object.defineProperty().
var o = { a:0 }
Object.defineProperty(o, "b", { get: function () { return this.a + 1; } });
console.log(o.b) // Runs the getter, which yields a + 1 (which is 1)