Javascript switch(true) 执行错误语句？

Question

Im looping over a collection of coordinate values and doing math on the coordinates to see if the calculated values are in a hashmap. if they are in the hash map then I want to run an additional function. since I had multiple cases I wanted to check for each coord in the collection, I figured a switch statement would be cool to use to replace my if statements so all my checks could be visually and logically grouped. When I replaced my if statements with a switch, my code returned bad results. When I debugged, I realized the switch statements would sometimes execute even when the case was false(I added console.logs to output the result of the same switch condition and it would print false, but should only run when true). Here is a small example:

var idm = {0:1, 3:1, 9:1, 10:1, 11:1, 12:1, 20:1, 21:1, 23:1}

var findNeighbors = function(b) {

    var u,d,l,r,lRow,rRow;
    var currentBuilding = parseInt(b);
    var currRow = Math.floor(currentBuilding/column);

    //remove value from map so we dont recount it.
    delete idm[currentBuilding];

    u = currentBuilding - column;
    d = currentBuilding + column;
    l = currentBuilding - 1;
    lRow = Math.floor(l/column);
    r = currentBuilding + 1;
    rRow = Math.floor(r/column);

    console.log("current idx:" + currentBuilding);
    console.log("u:" + u + ", d:" + d + ", l:" + l + " r:" + r);
    // debugger;
    switch(true) {
      case (idm.hasOwnProperty(u) === true):
        console.log((idm.hasOwnProperty(u)));
        console.log("map has " + currentBuilding + " -> u: " + u);
        findNeighbors(u);
      case (idm.hasOwnProperty(d) === true):
        console.log((idm.hasOwnProperty(d)));
        console.log("map has " + currentBuilding + " -> d: " + d);
        findNeighbors(d);
      case (lRow === currRow && idm.hasOwnProperty(l) === true):
        console.log((lRow === currRow && idm.hasOwnProperty(l)));
        console.log("map has " + currentBuilding + " -> l: " + l);
        findNeighbors(l);
      case (rRow === currRow && idm.hasOwnProperty(r) === true):
        console.log((rRow === currRow && idm.hasOwnProperty(r)))
        console.log("map has " + currentBuilding + " -> r: " + u);
        findNeighbors(r);
    }
    console.log("---------------------------");
  }

Answer 1

I figured a switch statement would be cool to use to replace my if statements so all my checks could be visually and logically grouped.

Well, write code that works not code that looks cool. You were forgetting break statements, so the execution flow fell through - without evaluating the other case expressions after the first one matched. Btw switch ing on a constant is a horrible (uncool) practice.

Use standard if / else instead.