How to Scope

how-to-scope.js

/**
 * Reference "this"
 */
var self = this;

self.someOtherMethod = function (result) {
    var self = this;
    
    return new Promise(function (resolve, reject) {
        self.callbackMethod(result, function (error, result) {
            if (error) {
                return reject(error);
            }
            
            resolve(result);
        });
    });
}

someMethod()
    .then(function (result) {
        return self.someOtherMethod(result);
    });
    
/**
 * Bind "this"
 */
this.someOtherMethod = function (result) {
    return new Promise(function (resolve, reject) {
        this.callbackMethod(result, function (error, result) {
            if (error) {
                return reject(error);
            }
        
            resolve(result);
        });
    }.bind(this));
}
    
someMethod()
    .then(function (result) {
        return this.someOtherMethod(result);
    }.bind(this));

/**
 * Arrow functions (doesn't work without transpiling)
 */
this.someOtherMethod = (result) => {
    new Promise((resolve, reject) => {
        this.callbackMethod(result, (error, result) => {
            if (error) {
                return reject(error);
            }
    
            resolve(result);
        });
    });
}

someMethod()
    .then((result) => {
        return this.someOtherMethod(result);
    });

I know that technically I could just use I could just use .then(this.someOtherMethod); and the last bit could just be .then((result) => this.someOtherMethod(result)); but I was trying to keep the comparison more direct.