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    1.0.2 • Public • Published


    Access deep property-values, arrays and functions using a path. Written in TypeScript. Paths are parsed for performance.



    npm install propath --save


    import pp from "propath";
    const obj = {
      a: {
        b: "f",
        c: ["g", "h"],
        d: () => 'i',
        e: j => `${j}_k`,
    // Parse path
    const ab = pp('a.b');
    // Get value
    let value = ab.get(obj); // value === "f"
    // Return undefined if path doesn't exist
    const alm12 = pp('a.l.m[12]');
    value = alm12.get(obj); // typeof value === "undefined"
    // Return predictable value if path doesn't exist
    const ano0pOrHello = pp('a.n.o[0].p()', 'Hello');
    value = ano0pOrHello.get(obj); // value === "Hello"
    // Set value
    ab.set(obj, "l");
    value = ab.get(obj); // value === "l"
    // Has value
    let hasAB = ab.has(obj); // hasAB === true
    const hasABC = pp('a.b.c').has(obj); // hasABC === false
    // Delete value
    ab.delete(obj); // returns true if ab was found and deleted
    hasAB = ab.has(obj); // hasAB === false
    // Get value from array
    const ac0 = pp('a.c[0]');
    value = ac0.get(obj); // value === "g"
    value = pp('a.c[1]').get(obj); // value === "h"
    // Set value on array
    ac0.set(obj, 'm');
    value = ac0.get(obj); // value === "m"
    // Get value from function
    const ad = pp('a.d()');
    value = ad.get(obj) // value === "i"
    // Get value from parametrized function
    const param = 'n';
    value = pp(`a.e("${param}")`).get(); // value === "n_k"
    // -> Parameters are provided in JSON syntax

    How propath deals with inherited properties

    Propath doesn't differentiate between inherited and own properties.

    Full API + examples

    Import propath

    import pp from "propath";

    Parse property-path / instantiate propath

    const ab = pp<V, D>('a.b', 'DEFAULT');
    • Type V is the value type, the path is expected to return
    • Type D is the value type of the default value

    Default value parameter is optional.

    Property-path syntax

    Value access


    Values access is done by property-names separated by dots ..

    Array index


    Value access is done by index number in square brackets [ and ].

    Function call

    a.b.c("STRING", 6.7, false)

    Calling functions is done by parameters in round brackets ( and ).

    • Function calls cannot be nested, but can contain whitespace.
    • Parameters must be in JSON syntax, strings must be double quoted with "


    pp<T, D>(path :string, defaultValue :D) :<instance>

    If propath is imported as the name pp, it is called as a function with optional type parameters T specifying the type returned by the path and D specifying the type of the default value.

    • D can be omitted while T is provided.
    • Neither T nor D must be provided.
    • If T is omitted, return-type of .get will be any.
    • Default value can be omitted.

    .get(<obj>) :T|any|D|undefined

    Traverses the path, returns the value found in <obj> if the path can be traversed completely. If it cannot, the default value or undefined is returned.

    .set(<obj>, value) :boolean

    Traverses the path, sets the value if the path can be traversed completely in <obj>. If it cannot, false is returned.

    .has(<obj>) :boolean

    Traverses the path, return true if the path can be traversed completely in <obj>. If it cannot, false is returned.

    .delete(<obj>) :boolean

    Traverses the path, deletes the value and returns true if the path can be traversed completely in <obj>. If it cannot, false is returned.


    npm i propath

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