JavaScript replace doesn't work [duplicate]

问题:

This question already has an answer here:

• Replace method doesn't work 4 answers

function areaMe(area) {
    var barea = $('#barea').val();
    if (barea.indexOf(area) != -1) {
        alert ("..." + barea + "..." + area + "...");
        barea.replace(area, "cu"); // Remove
        alert ("..." + barea + "..." + area + "...");
    }
    else {
        barea += area + ' '; // Include.
    }
    $('#barea').val(barea);
}

回答1:

barea = barea.replace(area, "cu")

You need to assign it since String.prototype.replace isn't a mutator method.

回答2:

You need to assign the replaced value back to your variable:

barea = barea.replace(area, "cu");

回答3:

barea = barea.replace(area, "cu")