JSFiddle - React, Tailwind, and code Playground

JavaScript

var combinations = Math.pow(3, 8);
for (i = 0; i < combinations; i++) {
    n = "1";
    c = i;
    for (digit = 2; digit <= 9; digit++) {
        op = c % 3;
        if (op == 1) n += "+";
        if (op == 2) n += "-";
        n += digit;
        c = Math.floor(c / 3);
    }
    if (eval(n) === 100)
        console.log(n);
}