Add any string suffix to number.  #121

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1. mbostock commented on Aug 5, 2021

   

   mbostock

   on Aug 5, 2021

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   For a fixed suffix, the recommended way is to wrap the format function. For example:

   const formatNumber = d3.format("d"); 
   const formatCelsius = d => `${formatNumber(d)}°C`;

   You can also combine the two like so:

   const formatCelsius = (f => d => `${f(d)}°C`)(d3.format("d"));

   We could perhaps formalize this pattern as:

   const formatCelsius = d3.format("d", (f, d) => `${f(d)}°C`);

   Or maybe make the arguments order-dependent to allow pre- (e.g., multiplying by 100) and post-formatting:

   const formatCelsius = d3.format("d", s => `${s}°C`);

   👍React with 👍3Reacted by Shreshth Mohan, Holger Bruch and Ryan Williams
2. mbostock commented on Jan 14, 2026

   

   mbostock

   on Jan 14, 2026

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   This was secretly added in #135. You can now pass an options second argument to d3.format that accepts a suffix (and prefix). For example:

   d3.format("d", {suffix: "°C"})(25) // "25°C"

   The advantage of this approach over the above wrappers is that it works correctly with respect to some of the more advanced formatting directives, such as parentheses for negative numbers.

   d3.format("(d", {suffix: "°C"})(-25) // "(25°C)"
3. mbostock

   closed this as completedon Jan 14, 2026