How to Implement a Safe Data Get Function in Javascript?

In Javascript, given object var x = {a: {b: {c: “value”} } }, we can retrieve/access the field by x.a.b.c However, if a field doesn’t exist, exception will be thrown and the code will stop running.

Let’s implement a safeGet function that allows you to easily retrieve the field and return undefined if a field doesn’t exist. For example,

var data = { a: { b: { c: 'HelloACM' } } }
safeGet(data, 'a.b.c') // => HelloACM
safeGet(data, 'a.b.c.d') // => undefined
safeGet(data, 'a.b.c.d.e.f.g') // => undefined
console.log("hello"); // "hello" will be printed

The Javascript implementation of safeGet is simple: split the path string and iterate the array and navigate the pointer to the fields. Iterating the array can be done via forEach:

const safeGet = (data, path) => {
  if (!path) return undefined;
  let found = true;
  path.split(".").forEach(function(v) {
    if (data[v]) {
      data = data[v];
    } else {
      found = false;
      return;
    }
  });
  return found ? data : undefined;
}

We can do a while loop and using .shift() method to pop up the first element in the array one by one.

const safeGet = (data, path) => {
    if (!path) return undefined;
    let paths = path.split('.');
    let res = data;
    while (paths.length) {
        res = res[paths.shift()]
        if (!res) return undefined;
    }
    return res;
}

–EOF (The Ultimate Computing & Technology Blog) —