javascript - Javascript 中的动态 if 语句

Question

是否有将字符串转换为 if 语句中的条件的方法:

示例:

var condition = "a == b && ( a > 5 || b > 5)";

if(condition) {
    alert("succes");
}

Answer 1

eval() 的更安全替代方案可能是 Function()。

var condition = "4 == 4 && ( 10 > 5 || 9 > 5)";
var evaluate = (c) => Function(`return ${c}`)();

if(evaluate(condition)) {
    alert("succes");
}

Per MDN:

eval() is a dangerous function, which executes the code it's passed with the privileges of the caller. If you run eval() with a string that could be affected by a malicious party, you may end up running malicious code on the user's machine with the permissions of your webpage / extension. More importantly, a third-party code can see the scope in which eval() was invoked, which can lead to possible attacks in ways to which the similar Function is not susceptible.