I already know that apply and call are similar functions which setthis (context of a function).
The difference is with the way
They all attach this into function (or object) and the difference is in the function invocation (see below).
call attaches this into function and executes the function immediately:
var person = {
name: "James Smith",
hello: function(thing) {
console.log(this.name + " says hello " + thing);
}
}
person.hello("world"); // output: "James Smith says hello world"
person.hello.call({ name: "Jim Smith" }, "world"); // output: "Jim Smith says hello world"
bind attaches this into function and it needs to be invoked separately like this:
var person = {
name: "James Smith",
hello: function(thing) {
console.log(this.name + " says hello " + thing);
}
}
person.hello("world"); // output: "James Smith says hello world"
var helloFunc = person.hello.bind({ name: "Jim Smith" });
helloFunc("world"); // output: Jim Smith says hello world"
or like this:
...
var helloFunc = person.hello.bind({ name: "Jim Smith" }, "world");
helloFunc(); // output: Jim Smith says hello world"
apply is similar to call except that it takes an array-like object instead of listing the arguments out one at a time:
function personContainer() {
var person = {
name: "James Smith",
hello: function() {
console.log(this.name + " says hello " + arguments[1]);
}
}
person.hello.apply(person, arguments);
}
personContainer("world", "mars"); // output: "James Smith says hello mars", note: arguments[0] = "world" , arguments[1] = "mars"