I can confirm Espruino is running fine on my ruuvi.

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|| http://espruino.com

1v93 Copyright 2016 G.Williams

Espruino is Open Source. Our work is supported

only by sales of official boards and donations:

http://espruino.com/Donate

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onInit()

=undefined

{ βxβ: 27.34375, βyβ: 27.34375, βzβ: 1015.625 }

{ βxβ: 23.4375, βyβ: 23.4375, βzβ: 1011.71875 }

{ βxβ: 218.75, βyβ: -386.71875, βzβ: 1023.4375 }

{ βxβ: 316.40625, βyβ: 449.21875, βzβ: 742.1875 }

{ βxβ: 105.46875, βyβ: 66.40625, βzβ: 808.59375 }

{ βxβ: -562.5, βyβ: -847.65625, βzβ: 281.25 }

{ βxβ: 27.34375, βyβ: -285.15625, βzβ: -855.46875 }

{ βxβ: 292.96875, βyβ: -753.90625, βzβ: -74.21875 }

{ βxβ: -82.03125, βyβ: 11.71875, βzβ: 3.90625 }

{ βxβ: -378.90625, βyβ: 574.21875, βzβ: -1285.15625 }

{ βxβ: 898.4375, βyβ: -859.375, βzβ: 843.75 }

{ βxβ: 410.15625, βyβ: -695.3125, βzβ: 1546.875 }

{ βxβ: 27.34375, βyβ: -3.90625, βzβ: 1011.71875 }

{ βxβ: 27.34375, βyβ: -11.71875, βzβ: 1019.53125 }

I downloaded via dfu, and waited until I could see ruuvitag in Espruino ide.