Function Invocation
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function hello(thing)
{
console.log(this + " says hello " + thing);
}
hello.call("Yehuda", "world")
//=> Yehuda says hello world
简单的函数调用
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function hello(thing) {
console.log("Hello " + thing);
}
// this:
hello("world")
// es5模式下等价于:
hello.call(window, "world");
// es5 严格模式下等价于
hello.call(undefined,'world');
函数指令的理解(function invocation)
一个函数指令例如：fn(…args) 等价于 fn.call(window [ES5-strict: undefined], …args).
匿名函数(function() {})() 等价于 (function(){}).call(window [ES5-strict: undefined).
####方法调用
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var person = {
name: "Brendan Eich",
hello: function(thing) {
console.log(this + " says hello " + thing);
}
}
// this:
person.hello("world")
// 等价于desugars to this:
person.hello.call(person, "world");
使用 Function.prototype.bind
有时为了方便对函数中的常量进行引用
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var person = {
name: "Brendan Eich",
hello: function(thing) {
console.log(this.name + " says hello " + thing);
}
}
var boundHello = function(thing) {
return person.hello.call(person, thing);
//第二个person保证了对person对象name的调用
}
boundHello("world");
//Brendan Eich says hello world