判断APP版本号大于等于当前版本

function compare(a, b) {
    if (a === b) {
       return 0;
    }
    var a_components = a.split(".");
    var b_components = b.split(".");
    var len = Math.min(a_components.length, b_components.length);
    for (var i = 0; i < len; i++) {
        if (parseInt(a_components[i]) > parseInt(b_components[i])) {
            return 1;
        }

        if (parseInt(a_components[i]) < parseInt(b_components[i])) {
            return -1;
        }
    }

    if (a_components.length > b_components.length) {
        return 1;
    }

    if (a_components.length < b_components.length) {
        return -1;
    }
    return 0;
}

console.log(compare("1", "2"));
console.log(compare("2", "1"));
console.log(compare("1.0", "1.0"));
console.log(compare("2.0", "1.0"));
console.log(compare("1.0", "2.0"));
console.log(compare("1.0.1", "1.0"));