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Simon Mannes
Simon Mannes

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3 Quick Tips to Convert Types In JavaScript

JavaScript has 6 primitive data types.

They are string, number, boolean, null, undefined, and symbol.

What's a symbol you ask? ECMAScript 2015 introduced them. They are a way to create globally unique values/identifiers with descriptions. This article does a great job explaining them.

And then there are objects. We will talk about them in another article.

Here are 3 quick tips for converting data to one specific primitive:

  • Boolean conversion. All JS values are truthy, except "", null, undefined, NaN, 0, and false. You can explicitly convert values to a boolean by using !!. !!0 === false && !!NaN === false && !!"" === false.
  • String conversion. Convert any primitive value to a string by adding an empty string. null + "" === "null". Since ES6 you can also use template strings for this: `${null}` === "null".
  • Number conversion. The primitive values string, null, and boolean can be converted to numbers with +. +null === 0 && +true === 1 && +false === 0 && +'0' === 0 && +'100' === 100.

You can also use the global methods String(), Number(), and Boolean().
They make your conversion explicit and readable.

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