在ajax请求正文上添加“ =”

Question

I'm trying to send an ajax request but when i send the variable "newValue" which is a String the server alwasy gets the content plus a "=". So if i send "20.09.2009" the server gets "20.09.2009=". Why? I cant get rid of this. Below is my code: Do i have to send specific headers?

$.ajax({
        url: url,
        dataType: 'json',
        type: 'POST',
        data: newValue,
        success: function(data) {
            if (data.perrorCode){//there is a validation error
                this.setState({error: `Validation Error. Expected format: ${data.perrorMessage}. Got format: ${data.pvalue}`});
                callback(false);
            } else
                callback(true);
        }.bind(this),
        error: function(xhr, status, err) {
            console.error(url, status, err.toString());
        }.bind(this)

If i print out the value right before, there is no "=". If I use advanced Rest Client addon for google chrome and set the exact same thing, the server responds correctly as he gets only "20.09.2009"

Answer 1

As @Quentin suggested, I've added the attribute contentType: 'text/plain' and my problem was gone.