{"id":13681,"date":"2021-03-02T05:50:11","date_gmt":"2021-03-02T13:50:11","guid":{"rendered":"https:\/\/www.microsoft.com\/en-us\/power-platform\/blog\/power-apps\/what-is-microsoft-power-fx\/"},"modified":"2025-06-11T07:55:26","modified_gmt":"2025-06-11T14:55:26","slug":"what-is-microsoft-power-fx","status":"publish","type":"post","link":"https:\/\/www.microsoft.com\/en-us\/power-platform\/blog\/power-apps\/what-is-microsoft-power-fx\/","title":{"rendered":"What is Microsoft Power Fx?"},"content":{"rendered":"

Microsoft Power Fx is the low code language for expressing logic across the Microsoft Power Platform<\/a>. \u00a0It is the same language that is at the heart of Microsoft Power Apps canvas apps<\/a>\u00a0today and is inspired by Microsoft Excel<\/a>.\u00a0 \u00a0It enables the full spectrum of development from “no code” to “pro code” with no cliffs in between, enabling diverse teams to collaborate and save time and expense.\u00a0 We are very excited to bring it to more of the Power Platform and to share it with everyone as open source.\u00a0 Only through a strong user community can a language grow and flourish.<\/p>\n

Today\u2019s announcement<\/a>\u00a0is a statement of direction.\u00a0 We have a lot of work to do to extract Power Fx from the Power Apps home where it grew up.\u00a0 We are actively working to integrate Power Fx into\u00a0Microsoft Power Virtual Agents<\/a>, Microsoft Dataverse<\/a>, and Model-driven Power Apps<\/a>. We’ll use these as our test beds for getting the packages right for open source sharing.\u00a0 We have setup a GitHub repository for our open source at https:\/\/github.com\/microsoft\/Power-Fx<\/a> where you can begin to share your thoughts about the language.\u00a0 There isn\u2019t much there today, just a copy of some early documentation<\/a> which we are also in the process of extracting from Power Apps.<\/p>\n

When we say \u201cacross the Microsoft Power Platform\u201d you may be wondering if there are any implications for Power BI\u2019s existing M<\/a> and DAX<\/a> languages.\u00a0 The answer is no.\u00a0 Power Fx is complimentary to and has no impact on these languages, all three will live happily together.\u00a0 M and DAX focus on reading, shaping, joining, and summarizing large amounts of data while Power Fx focuses on reading and writing smaller sets of relational data.<\/p>\n

Think Excel<\/h2>\n

What if you could build an app as easily as you build a spreadsheet?<\/p>\n

What if you could leverage your existing spreadsheet knowledge?<\/p>\n

These were the questions that inspired the creation of Power Apps and Power Fx.\u00a0 Hundreds of millions of people create spreadsheets with Excel every day, let\u2019s bring app creation to them that is easy and leverages Excel concepts that they already know.<\/p>\n

Replicating Excel\u2019s expression language for data types, operators, and core functions is fairly straightforward.\u00a0 This table shows all of Power Fx\u2019s pure functions, the ones marked in green are identical or very close to Excel\u2019s version:<\/p>\n

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Excel has many more functions than this and we are adding more all the time to Power Fx. We also meet with the Excel team and discuss what they are adding next and how we can add functions that stay consistent with their direction.<\/p>\n

But you don\u2019t just write expressions<\/em> in Excel, you write formulas <\/em>or recipes for how to calculate a specific cell\u2019s value.\u00a0 A1 = B2 * 2<\/strong> is a formula that defines the value of A1<\/strong> at all times and is recalculated automatically as B2<\/strong> changes.<\/p>\n

Power Fx follows this same formula pattern<\/em>.\u00a0 Cells are replaced with the properties of controls or objects.\u00a0 Here\u2019s an example where we have taken this Excel formula from Stack Overflow for reverse string search<\/a>:<\/p>\n

Excel with the formula: =RIGHT(A1,LEN(A1)-FIND(\"|\",SUBSTITUTE(A1,\" \",\"|\",LEN(A1)-LEN(SUBSTITUTE(A1,\" \",\"\")))))<\/p>\n

And created a Power Fx formula from it.\u00a0 All that is different is that the references to cells have been replaced with references to control properties:<\/p>\n

\"\"<\/p>\n

Not only does this same syntax and same functions work in Power Fx, but notice something else in the animation.\u00a0 As Input.Text<\/strong> changes (the top box), Label.Text<\/strong>\u00a0(the bottom box) is automatically recalculated.\u00a0 The app is behaving<\/em> like a spreadsheet, it is recalculating<\/em>.<\/p>\n

Here is another more colorful example that uses a formula for the Fill<\/strong> color of the screen.\u00a0 As the sliders that control Red, Green, and Blue are changed, the background color automatically changes, as it is being recalculated:<\/p>\n

\"Power<\/p>\n

There are no OnChange events for the slider controls as would be common in other languages. \u00a0In fact, there is no way to explicitly set the Fill property value at all<\/em>.\u00a0 Which has a huge advantage: there is only one source of truth.\u00a0 If the color isn\u2019t working correctly, one only needs to look to this one formula to understand why.\u00a0 You don\u2019t need to search through your app to find a rogue piece of code that set the property at an unexpected time.\u00a0 In fact there is no time element, the correct formula values are always maintained.<\/p>\n

Note something else in the animation.\u00a0 As the sliders are set to a dark color, the labels for Red, Green, and Blue change to white to compensate.\u00a0 This is done through a simple formula on each label control’s Color<\/strong> property:<\/p>\n

\"Power<\/p>\n

What’s great about this is that it is isolated from what is happening for the Fill<\/strong> color,\u00a0\u00a0these are two entirely different calculations.\u00a0<\/em>\u00a0Instead of large monolithic procedures, Power Fx logic is typically lots of smaller formulas that are independent.\u00a0 That’s easier to understand and enables enhancements without disturbing existing logic.<\/p>\n

Power Fx is a declarative language, just as Excel is.\u00a0 The maker defines what<\/em> behavior they want, but it is up to the system to determine and optimize how<\/em> and when<\/em> to accomplish it. \u00a0To make that practical, most work is done through pure functions without side effects, making Power Fx also a functional language, again just as Excel is.<\/p>\n

Now there is a time and a place for imperative, step-by-step, logic and Power Fx offers this too.\u00a0 Apps write back changes to databases and start automations with the press of a button, while spreadsheets do not do these things.\u00a0 Whenever possible, for all the benefits cited above and consistency with Excel, we favor the declarative approach.<\/p>\n

Low code<\/h2>\n

Power Fx describes business logic in concise, yet powerful, formulas.\u00a0 Most logic can be reduced to one-liners with plenty of expressiveness and control for more complex needs.\u00a0 The goal is to keep the number of concepts a maker needs to understand to a minimum, ideally no more than an Excel user would already know.<\/p>\n

For example, to lookup the first name of the employee for an order, one would write the following Power Fx.\u00a0 Beyond Excel concepts, the only added concept used here is “.” notation for drilling into a data structure, in this case for .Employee.’First Name’<\/strong>.\u00a0 This animation shows the mapping between the parts of the Power Fx formula and the concepts that need to be explicitly coded in the equivalent JavaScript.<\/p>\n

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Let\u2019s look more in depth at all the things that Power Fx is doing for us and the freedom it has to optimize because the formula was declarative:<\/p>\n