Question

This question is for objects in Javascript.

I notice that I can add a string and an Error object just fine, and the Error object text is concatenated with no problems.

try {
    throw new Error('Sample Text');
} catch (error) {
    document.writeln('There was an error. ' + error); // Go plus sign!
}

This outputs There was an error. Error: Sample Text which is pretty cool. The Error object knew what string I wanted to concatenate. My own objects do not act nice like this.

var myObject = (function () {
    var text = 'Text I want to concat.',
        get_text = function () { return text; },
        that = {};
    that.get_text = get_text;
    return that;
}());
document.writeln('What does my object say: ' + myObject); // Uncool

My own object outputs What does my object say: [object Object] and does not act nice like the Error object does.

I do not want [object Object] to be output. How can I change what string myObject spits out when being added to a string?

Answer 1

You should give your objects a toString method that returns the appropriate string. So you just need to rename get_text to toString. You could write it something like this:

var myObject = (function () {
    var text = 'Text I want to concat.';
    return {
      toString : function () { return text }
    };
}());