在将JSON对象推送到Javascript之前过滤数组

Question

it looks like easy but I kind of stuck in trying to figure out how to filter data before pushing json data into javascript array.

//push data into javascript array [timestamp,value]
dataJSON2 = [];
for (i in parsed2) {

    if (parsed2[i].value == 'open' || parsed2[i].value == 'true'  ) {
        thevalue = 1;
    } else if (parsed2[i].value == 'closed' || parsed2[i].value == 'false' ) {
        thevalue = 0;
    } else {
        thevalue = parsed2[i].value;
    }
    dataJSON2.push( [ (parsed2[i].timestamp),
    parseFloat (thevalue) ] );

}

what I am trying to accomplish is if current thevalue var is the same with the previous thevalue then it would discard the data and go to the next i until it return different value. It would be easy if using for looping but I don't know different way to push json object rather than for..in , nor to use filtering i value before pushing it.

Answer 1

var dataJSON2 = [], previous;
for (i in parsed2) {
    if (parsed2[i].value === 'open' || parsed2[i].value === 'true'  ) {
        thevalue = 1;
    } else if (parsed2[i].value === 'closed' || parsed2[i].value === 'false' ) {
        thevalue = 0;
    } else {
        thevalue = parsed2[i].value;
    }
    if (previous === thevalue) continue;
    previous = thevalue;
    dataJSON2.push( [ (parsed2[i].timestamp), parseFloat (thevalue) ] );
}

Answer 2

This would check for previous value with the current value and skip it if they are same

dataJSON2 = [];

var lastVal = parsed2 && parsed2[0];
for (var i = 1; i < parsed2.length; i++) {
    if (lastVal !== parsed2[i].value) {
        dataJSON2.push([(parsed2[i].timestamp), parseFloat(parsed2[i].value)]);
        lastVal = parsed2[i];
    }
}

Answer 3

Extracted from Array.indexOf from MDN

Create a function like this

if (!Array.prototype.indexOf) {
  Array.prototype.indexOf = function (searchElement /*, fromIndex */ ) {
    'use strict';
    if (this == null) {
      throw new TypeError();
    }
    var n, k, t = Object(this),
        len = t.length >>> 0;

    if (len === 0) {
      return -1;
    }
    n = 0;
    if (arguments.length > 1) {
      n = Number(arguments[1]);
      if (n != n) { // shortcut for verifying if it's NaN
        n = 0;
      } else if (n != 0 && n != Infinity && n != -Infinity) {
        n = (n > 0 || -1) * Math.floor(Math.abs(n));
      }
    }
    if (n >= len) {
      return -1;
    }
    for (k = n >= 0 ? n : Math.max(len - Math.abs(n), 0); k < len; k++) {
      if (k in t && t[k] === searchElement) {
        return k;
      }
    }
    return -1;
  };
}

and use indexOf like this

if (dataJSON2.indexOf( [ (parsed2[i].timestamp), parseFloat (thevalue) ] ) == -1){
    dataJSON2.push( [ (parsed2[i].timestamp), parseFloat (thevalue) ] );
}