为什么即使条件为假，这个“ IF”也总是执行？

Question

This is my code:

$('.btn-back').off('click').on('click', function (event) {
    var valid = carInfo.validate();
    if (valid) {
        event.preventDefault();
    }
});

the sentence event.preventDefault() always executes no matter what value valid is.

When I change the code to

$('.btn-back').off('click').on('click', function (event) {
    var valid = carInfo.validate();
    if (valid) {
        event.preventDefault();
    } else {

    }
});

it runs the way it should be. Maybe it's something related to Automatic Semicolon Insertion (ASI).

Answer 1

Use the jQuery Validation plugin way:

carInfo.validate() will return Validator object .

So valid variable is always true . Use valid method from docs :

$('.btn-back').off('click').on('click', function (event) {
    carInfo.validate();
    if (carInfo.valid()) {
        event.preventDefault();
    }
});