# CodeMirror: Autocomplete demo

function getCompletions(token, context) { var found = [], start = token.string; function maybeAdd(str) { if (str.indexOf(start) == 0) found.push(str); } function gatherCompletions(obj) { if (typeof obj == "string") forEach(stringProps, maybeAdd); else if (obj instanceof Array) forEach(arrayProps, maybeAdd); else if (obj instanceof Function) forEach(funcProps, maybeAdd); for (var name in obj) maybeAdd(name); } if (context) { // If this is a property, see if it belongs to some object we can // find in the current environment. var obj = context.pop(), base; if (obj.className == "js-variable") base = window[obj.string]; else if (obj.className == "js-string") base = ""; else if (obj.className == "js-atom") base = 1; while (base != null && context.length) base = base[context.pop().string]; if (base != null) gatherCompletions(base); } else { // If not, just look in the window object and any local scope // (reading into JS mode internals to get at the local variables) for (var v = token.state.localVars; v; v = v.next) maybeAdd(v.name); gatherCompletions(window); forEach(keywords, maybeAdd); } return found; }

Press ctrl-space to activate autocompletion. See the code (here and here) to figure out how it works.