javascript - Using .includes method in a function

Question

I have a an object jsonRes[0] containing values which need to be removed based on a condition. The following works to remove null, missing values and those equal to zero in the stringified object:

function replacer(key, value) {
          // Filtering out properties
          if (value === null || value === 0 || value === "") {
            return undefined;
          }
          return value;
        } 

JSON.stringify(jsonRes[0], replacer, "")

However, when I add a condition using the the includes method, I receive an error:

function replacer(key, value) {
          // Filtering out properties
          if (value === null || value === 0 || value === "" || value.includes("$")) {
            return undefined;
          }
          return value;
        } 


Uncaught TypeError: value.includes is not a function

Why is this the case and is there a workaround?

Answer 1

You can use String.indexOf() instead of String.includes, As it is available in ES6 and not supported in IE at all.

typeof value == "string" && value.indexOf('$') > -1

Also note if value is not string type it will still raise an error boolean, Number doesn't the the method. You can use typeof to validate whether value is a string.