我不能在jquery里面调用php函数[重复]

Question

This question already has an answer here:

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I'm trying to call PHP funcation via jquery but It's not working

echo "<script>
$('.btn').click(function () {
    if($(\".main-input-box\").val().length > 0){
        $(resultContainer).css('display','block');
        getData();
    }else{
        alert('aaa');
    }
});
</script>";

function getData(){
 echo "test";
}

</div>