You can use reduce to create such function.
function getMin(data) {
return data.reduce(function(r, e, i) {
let absR = Math.abs(r), absE = Math.abs(e);
if (absR > absE || i == 0 || (absR == absE && e > r)) r = e
return r
})
}
console.log(getMin([1.5, -1, 0, 5, 5.5, -4]))
console.log(getMin([1.5, -1, 5, 5.5, -4]))
console.log(getMin([1, -1, 5, 5.5, -4]))
console.log(getMin([-1, 1, 5, 5.5, -4]))
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solved How to get smallest difference value from an array in Javascript