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JavaScript JavaScript Objects Object Basics Set the Value of Object Properties

Marius Kressin
Marius Kressin
10,038 Points

String Object

Is it possible to add a property to the string object, like

String.isAllUppercase = ( String === String.toUpperCase );

1 Answer

Steven Parker
Steven Parker
231,236 Points

For practical purposes, it might be better to just define a function that can be passed a string argument:

const isAllUppercase = str => str == str.toUpperCase();

Yet you can modify Strings, but with a different and not quite so direct syntax. If you wanted to define a new method, it could be done like this:

String.prototype.isAllUppercase = function() { return this == this.toUpperCase(); };

But it looks like what you really want is a new "getter method" (one that can be invoked without parentheses), which requires an even more complex syntax.

Object.defineProperty(String.prototype, "isAllUppercase", {
    get() { return this == this.toUpperCase(); }
});

Also note that either way, when you invoke toUpperCase, you must add parentheses to its name.

Marius Kressin
Marius Kressin
10,038 Points

I don't think I'll understand this until a while later, but thank you anyway.