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Javascript assignment operator returns the assigned value

20.01.2025
Javascript Stencil

While working on Stencil, i discovered that Javascript’s assignment operator returns the assigned value. This behaviour allows us to reuse the result of the a function multiple times within a single line of code.

const slotName = (newChild['s-sn'] = getSlotName(newChild));

You can view the whole code in GitHub

In this code, we assign the return value of getSlotName to slotName and 's-sn' property of newChild.

After writing JS for few years, i almost forgot this thing and never used it before.

Is it good for readability, dx, efficiency? I am not sure… but it is fun to discover a little aspect of assignment operator.

Official Docs