JavaScript - method chaining

jquery.js

$.fn.redBorder = function () {
    $(this).css("border", "1px solid red");
    return this;
    
    //  or shorter "return $(this).css("border", "1px solid red");"
    
};

$.fn.greyBackground = function () {
    return $(this).css("background-color", "grey");
};

$.fn.innTxt = function (txt) {
    return $(this).html(txt);

};


$('#main').redBorder().greyBackground().innTxt("testing chaining");

js.js

var value = 0;
var obj = {
    increase: function(val) {
        value = value + val;
        return obj;
    },
    decrease: function(val) {
        value = value - val;
        return obj;
    }
}
obj.increase(5).increase(2).decrease(1);
console.log(value); // 6