jQuery if语句带有变量数学运算符

Question

所以我正在寻找类似于这个问题python if语句的变量数学运算符,但在jQuery/Javascript中

基本上是这样的

var one = "4";

var two = "6";

var op = "==";

if (one op two) {
//do something
}

这可能吗？

Answer 1

你可以定义很多二进制函数:

var operators = {
    "==": function(a,b){return a==b;},
    "<=": function(a,b){return a<=b;},
    ">=": function(a,b){return a>=b;},
    "<": function(a,b){return a<b;},
    ">": function(a,b){return a>b;},
    …
};

var one = "4",
    two = "6",
    op = "==";
if (op in operators && operators[op](+one, +two)) {
    //do something
}

如果您不想生成如此大的对象并且没有复杂的函数,那么您也可以在运行中生成它们(使用一些eval魔法):

var validOps = /^([!=<>]=|<|>)$/,
    operators = {};
function check(op, x, y) {
    if (arguments.length > 1)
        return check(op)(x, y);
    if (op in operators)
        return operators[op];
    if (validOps.test(op))
        return operators[op] = new Function("a","b","return a "+op+" b;");
    return function(a, b){return false;};
}

if (check("==", 4, 6)) {
    // do something
}