Question

So I have 4 input type text that are optional (no obligation to fill in) but if the user fills in one of them, then I want him to fill them all.

Resume:
– If user fills in 0 input => no obligation, he can leave them blank;
– If user fills in 1< input => must fill them all.

How can I do that with jQuery?

Answer 1

Here is one option:

$("form").on("submit", function() {
    var filled = $(this).find("input").filter(function() {
        return this.value.length > 0;
    });

    if (filled.length > 0) {
        alert("Fill 'em all!");
        return false;
    }
    return true;
});

DEMO: http://jsfiddle.net/xw9pb/