Javascript / Typescript->访问函数的先前作用域

Question

Is it possible to access the previous scope of a function in Javascript? Or is it possible to automaticaly assign "this" to a parameter in typescript when calling a function? (so I have the previous scope)

for example: (a Function defined in my class Queryable)

    Where(filter: (part: T) => boolean): Queryable<T> {
    var ast = acorn.parse("(" + filter.toString() + ")"); ...

and I use it from outside:

var aa = new Queryable<ITest>();
var jj = "bb";
aa.Where(x => x.content == "aa" && x.bb.content == jj || x.form.Contains("Hallo"));

now inside my Where function, I need to get the value of "jj"

Mabey a little bit more Code helps:

class Queryable<T> {

    Where(filter: (part: T) => boolean): IQueryable<T> {
        var ast = acorn.parse("(" + filter.toString() + ")");

        return null;
    }
}

interface String {
    Contains(par: String): boolean;
    StartsWith(par: String): boolean;
    EndsWith(par: String): boolean;
}

interface ITest {
     content: string;
     form: string;
     href: string;
     bb: ITest;
     cc: ITest[];
}

function test() {
     var aa = new Queryable<ITest>();
     var jj = "bb";
     aa.Where(x => x.content == "aa" && x.bb.content == jj || x.form.Contains("Hallo"));
 }

 test();

And inside the "Where" I need to access the Variables wich were used in the function in his parameter

Answer 1

I do not think its possible to access 'previous' scope except for the case when its global scope (see more here ). And even if it where possible and you could get reference to 'this' it will not allow you to access variables.

I would recommend to rework your approach and use instead of variables - objects of classes with properties designed to hold all required info. Then you will be able to pass instances of such parent object along with function calls and access its properties as needed.

Roughly like this:

class Queryable<T> 
{
    public Where(parent: any, filter: (part: T) => boolean): IQueryable<T> 
    {
        var jj = parent.jj;
        var ast = acorn.parse("(" + filter.toString() + ")");
        return null;
    }
}

class Test 
{
    public jj;

    public Run()
    {
        this.jj = "bb";
        let aa = new Queryable<ITest>();
        aa.Where(this, x => x.content == "aa" && x.bb.content == this.jj || x.form.Contains("Hallo"));
    }
}