What is js-yaml-source-map?

js-yaml-source-map is a tool that helps your code remember exactly where each piece of data came from in a YAML file. When a program reads a YAML file, it usually turns the text into a plain data object, losing track of original line numbers and positions. This library keeps that connection alive, so if you have a specific value in mind, you can find out exactly which line and column it lives on in the original file. You use it alongside js-yaml, a popular YAML parser. As js-yaml reads your file, this tool quietly listens and builds a map of every piece of data and its location. Later, you can ask it to look up any value using a simple path, like "fruits" or "people.0.age," and it returns the line number, column, and character position where that value appears in the source text. This is useful for anyone building tools that work with YAML files and need to report errors or highlight specific sections. For example, if you are building a configuration validator and a user has a mistake on a deeply nested setting, you could use this to tell them exactly which line to fix. Instead of just saying "something is wrong," your tool could point them to line 16, column 12, where the problematic value actually sits. The library handles a few different ways of asking for locations. You can use a dotted string like "states.NY.capital," an array-style path like ".people[1].name," or pass an array of keys. The README does note some limitations: it does not work with files containing multiple YAML documents in one file, and it cannot handle arrays or objects used as keys in the YAML itself.