为什么ParseFloat无法在我的json对象上正常工作

Question

Can someone help me or explain why the data that is written the same is not converted properly to the notation I need.

I can't seem to find out why my object wouldn't convert properly as the example where it does convert properly.

 var data2_JSON = document.getElementById('JSON2').value; var obj2 = JSON.parse(data2_JSON); function getMaxY() { var max = 0; //!! only every other item in array is having sumps2 for(var i = 1; i < obj2.dataset2.length; i+=2) { if(Number(obj2.dataset2[i].p1) > max) { max = Number(obj2.dataset2[i].p1); } } return Number(max|0); // convert to integer number } var sNum = "1.23e-2"; alert(parseFloat(sNum)); alert(parseFloat(obj2.dataset2[4].p1)); 

  <textarea id="JSON2"> { "dataset2": [ {"p1" : "2.097E-15 "} ,{"sumps2" :" 12"}, {"p1" : "3.6039E-13 "} ,{"sumps2" :" 5"}, {"p1" : "5.6446E-16 "} ,{"sumps2" :" 14"}, {"p1" : "-4.9850E-20 "} ,{"sumps2" :" 7"}, {"p1" : "-3.430E-21 "} ,{"sumps2" :" 6"}, {"p1" : "9.8509E-20 "} ,{"sumps2" :" 7"}, {"p1" : "6.4500E-20 "} ,{"sumps2" :" 4"}, {"p1" : "-4.2150E-20 "} ,{"sumps2" :" 17"}, {"p1" : "-1.835E-21 "} ,{"sumps2" :" 11"}, {"p1" : "-4.5872E-20 "} ,{"sumps2" :" 13"}, {"p1" : "-9.7921E-21 "} ,{"sumps2" :" 9"}, {"p1" : "-1.2206E-19 "} ,{"sumps2" :" 4"}, {"p1" : "-3.843E-20 "} ,{"sumps2" :" 3"}, {"p1" : "-2.1871E-20 "} ,{"sumps2" :" 10"}, {"p1" : "3.0353E-20 "} ,{"sumps2" :" 7"}, {"p1" : "3.4013E-20 "} ,{"sumps2" :" 17"}, {"p1" : "-1.20536E-19 "} ,{"sumps2" :" 17"}, {"p1" : "2.9374E-19 "} ,{"sumps2" :" 12"}, {"p1" : "9.5229E-20 "} ,{"sumps2" :" 16"}, {"p1" : "0.15006E-15 "} ,{"sumps2" :" 6"}, {"p1" : "1.01736E-20 "} ,{"sumps2" :" 10"}, {"p1" : "4.966E-21 "} ,{"sumps2" :" 1"}, {"p1" : "4.08210E-16 "} ,{"sumps2" :" 7"}, {"p1" : "2.878973E-15 "} ,{"sumps2" :" 12"}, {"p1" : "2.49E-15 "} ,{"sumps2" :" 3"}, {"p1" : "4.4632E-15 "} ,{"sumps2" :" 9"}, {"p1" : "2.35454E-15 "} ,{"sumps2" :" 6"}, {"p1" : "7E-18 "} ,{"sumps2" :" 2"}, {"p1" : "9.53764E-15 "} ,{"sumps2" :" 4"}, {"p1" : "3.32849E-15 "} ,{"sumps2" :" 7"}, {"p1" : "1.0E-16 "} ,{"sumps2" :" 8"}, {"p1" : "1.88E-11 "} ,{"sumps2" :" 8"}, {"p1" : "5.16E-21 "} ,{"sumps2" :" 3"}, {"p1" : "5.95492E-15 "} ,{"sumps2" :" 9"}, {"p1" : "4.2792E-16 "} ,{"sumps2" :" 5"}, {"p1" : "7.704E-17 "} ,{"sumps2" :" 12"}, {"p1" : "1.3051E-14 "} ,{"sumps2" :" 3"}, {"p1" : "4.809E-17 "} ,{"sumps2" :" 4"}, {"p1" : "7.092E-15 "} ,{"sumps2" :" 4"}, {"p1" : "4.8590E-15 "} ,{"sumps2" :" 15"}, {"p1" : "5.849955E-15 "} ,{"sumps2" :" 17"}, {"p1" : "1.7614E-15 "} ,{"sumps2" :" 7"}, {"p1" : "1.200E-16 "} ,{"sumps2" :" 2"}, {"p1" : "7.83718E-17 "} ,{"sumps2" :" 10"}, {"p1" : "0.01223E-15 "} ,{"sumps2" :" 3"}, {"p1" : "1.071167E-14 "} ,{"sumps2" :" 12"}, {"p1" : "3.91070E-16 "} ,{"sumps2" :" 14"}, {"p1" : "1.99E-12 "} ,{"sumps2" :" 5"}, {"p1" : "2.56763E-16 "} ,{"sumps2" :" 8"}, {"p1" : "4.4259E-16 "} ,{"sumps2" :" 5"}, {"p1" : "1.700E-15 "} ,{"sumps2" :" 4"}, {"p1" : "1.299202E-15 "} ,{"sumps2" :" 6"}, {"p1" : "1.516E-16 "} ,{"sumps2" :" 10"}, {"p1" : "1.889254E-13 "} ,{"sumps2" :" 5"}, {"p1" : "1.93754256E-13 "} ,{"sumps2" :" 4"}, {"p1" : "1.1994E-15 "} ,{"sumps2" :" 5"}, {"p1" : "2.9E-16 "} ,{"sumps2" :" 2"}, {"p1" : "6.6E-15 "} ,{"sumps2" :" 3"}, {"p1" : "2.99E-19 "} ,{"sumps2" :" 10"}, {"p1" : "6.6212E-16 "} ,{"sumps2" :" 3"}, {"p1" : "7.7389E-20 "} ,{"sumps2" :" 17"}, {"p1" : "3.10998E-15 "} ,{"sumps2" :" 7"}, {"p1" : "5.509E-14 "} ,{"sumps2" :" 5"}, {"p1" : "3.06E-17 "} ,{"sumps2" :" 3"}, {"p1" : "1.295235E-15 "} ,{"sumps2" :" 20"}, {"p1" : "6.3562E-16 "} ,{"sumps2" :" 7"}, {"p1" : "0.381E-15 "} ,{"sumps2" :" 3"}, {"p1" : "0.21525E-15 "} ,{"sumps2" :" 6"}, {"p1" : "2.048265E-15 "} ,{"sumps2" :" 8"}, {"p1" : "7.3505E-18 "} ,{"sumps2" :" 10"}, {"p1" : "1.7666E-20 "} ,{"sumps2" :" 9"}, {"p1" : "0.057E-15 "} ,{"sumps2" :" 9"}, {"p1" : "1.342243E-14 "} ,{"sumps2" :" 15"}, {"p1" : "2.4075E-19 "} ,{"sumps2" :" 5"}, {"p1" : "1.3037E-14 "} ,{"sumps2" :" 20"}, {"p1" : "4.76594E-16 "} ,{"sumps2" :" 3"}, {"p1" : "4.396862E-15 "} ,{"sumps2" :" 13"}, {"p1" : "1.5382E-15 "} ,{"sumps2" :" 12"}, {"p1" : "5.57316E-15 "} ,{"sumps2" :" 3"}, {"p1" : "7.9E-20 "} ,{"sumps2" :" 3"}, {"p1" : "7.6601E-17 "} ,{"sumps2" :" 3"}, {"p1" : "0E-15 "} ,{"sumps2" :" 6"}, {"p1" : "2.759E-14 "} ,{"sumps2" :" 10"}, {"p1" : "1.16338E-15 "} ,{"sumps2" :" 15"}, {"p1" : "39.3444E-15 "} ,{"sumps2" :" 2"}, {"p1" : "5.729370E-20 "} ,{"sumps2" :" 9"}, {"p1" : "1.48347E-16 "} ,{"sumps2" :" 19"}, {"p1" : "3.371E-15 "} ,{"sumps2" :" 4"}, {"p1" : "1.02649E-16 "} ,{"sumps2" :" 6"}, {"p1" : "0E-15 "} ,{"sumps2" :" 2"}, {"p1" : "5.753107E-15 "} ,{"sumps2" :" 16"}, {"p1" : "2.37227E-15 "} ,{"sumps2" :" 7"}, {"p1" : "1.02119E-14 "} ,{"sumps2" :" 15"}, {"p1" : "36.70E-15 "} ,{"sumps2" :" 3"}, {"p1" : "0.21E-15 "} ,{"sumps2" :" 3"}, {"p1" : "5.3E-16 "} ,{"sumps2" :" 15"}, {"p1" : "1.39825E-15 "} ,{"sumps2" :" 6"}, {"p1" : "5.82E-12 "} ,{"sumps2" :" 3"}, {"p1" : "5.582339E-15 "} ,{"sumps2" :" 17"}, {"p1" : "2.3090E-14 "} ,{"sumps2" :" 6"}, {"p1" : "0.206E-15 "} ,{"sumps2" :" 4"}, {"p1" : "1.17E-21 "} ,{"sumps2" :" 13"}, {"p1" : "0.6968E-15 "} ,{"sumps2" :" 5"}, {"p1" : "3.0092E-17 "} ,{"sumps2" :" 9"}, {"p1" : "17.727E-15 "} ,{"sumps2" :" 14"}, {"p1" : "7.36052E-17 "} ,{"sumps2" :" 6"}, {"p1" : "6.5E-11 "} ,{"sumps2" :" 5"}, {"p1" : "4.00530E-14 "} ,{"sumps2" :" 15"}, {"p1" : "1.5509E-14 "} ,{"sumps2" :" 6"}, {"p1" : "5.354E-15 "} ,{"sumps2" :" 13"}, {"p1" : "1.60E-16 "} ,{"sumps2" :" 1"}, {"p1" : "4.22765E-13 "} ,{"sumps2" :" 4"}, {"p1" : "425.05E-15 "} ,{"sumps2" :" 6"}, {"p1" : "11.5E-15 "} ,{"sumps2" :" 3"}, {"p1" : "5.65E-16 "} ,{"sumps2" :" 3"}, {"p1" : "5.1784338E-14 "} ,{"sumps2" :" 11"}, {"p1" : "3.6694515E-15 "} ,{"sumps2" :" 13"}, {"p1" : "0.44811E-15 "} ,{"sumps2" :" 2"}, {"p1" : "4.78924621E-13 "} ,{"sumps2" :" 3"}, {"p1" : "8.2E-16 "} ,{"sumps2" :" 8"}, {"p1" : "1.5422691E-14 "} ,{"sumps2" :" 19"}, {"p1" : "3.94E-15 "} ,{"sumps2" :" 3"}, {"p1" : "7.65E-15 "} ,{"sumps2" :" 3"}, {"p1" : "1.426028E-13 "} ,{"sumps2" :" 11"}, {"p1" : "5.96E-15 "} ,{"sumps2" :" 3"}, {"p1" : "2.78E-15 "} ,{"sumps2" :" 9"}, {"p1" : "1.302098E-15 "} ,{"sumps2" :" 5"}, {"p1" : "0.000235E-15 "} ,{"sumps2" :" 2"}, {"p1" : "0.00001235E-15 "} ,{"sumps2" :" 6"}, {"p1" : "5.94681E-17 "} ,{"sumps2" :" 18"}, {"p1" : "9.5913E-21 "} ,{"sumps2" :" 8"}, {"p1" : "5.94494E-14 "} ,{"sumps2" :" 12"}, {"p1" : "1.75E-20 "} ,{"sumps2" :" 7"}, {"p1" : "0.00724E-15 "} ,{"sumps2" :" 6"}, {"p1" : "4.732E-20 "} ,{"sumps2" :" 2"}, {"p1" : "2.54237E-14 "} ,{"sumps2" :" 5"}, {"p1" : "0.08837E-15 "} ,{"sumps2" :" 3"}, {"p1" : "8.30442E-16 "} ,{"sumps2" :" 12"}, {"p1" : "1.698E-15 "} ,{"sumps2" :" 3"}, {"p1" : "29.8087E-15 "} ,{"sumps2" :" 18"}, {"p1" : "0.5479E-15 "} ,{"sumps2" :" 2"}, {"p1" : "1.99573E-15 "} ,{"sumps2" :" 3"}, {"p1" : "3.7481E-15 "} ,{"sumps2" :" 19"}, {"p1" : "7.1229E-15 "} ,{"sumps2" :" 3"}, {"p1" : "1.046741E-13 "} ,{"sumps2" :" 17"}, {"p1" : "7.9592E-14 "} ,{"sumps2" :" 3"}, {"p1" : "1.097087E-14 "} ,{"sumps2" :" 5"}, {"p1" : "3.82E-15 "} ,{"sumps2" :" 8"}, {"p1" : "3.1722E-15 "} ,{"sumps2" :" 20"}, {"p1" : "3.38E-21 "} ,{"sumps2" :" 3"}, {"p1" : "4.923E-21 "} ,{"sumps2" :" 8"}, {"p1" : "0.7357E-15 "} ,{"sumps2" :" 3"}, {"p1" : "6.421E-15 "} ,{"sumps2" :" 8"}, {"p1" : "0.1525E-15 "} ,{"sumps2" :" 12"}, {"p1" : "3.798787E-15 "} ,{"sumps2" :" 15"}, {"p1" : "0.0267E-15 "} ,{"sumps2" :" 17"}, {"p1" : "0.03191E-15 "} ,{"sumps2" :" 9"}, {"p1" : "9.15201E-15 "} ,{"sumps2" :" 13"}, {"p1" : "5.500309E-14 "} ,{"sumps2" :" 3"}, {"p1" : "6.853E-19 "} ,{"sumps2" :" 12"}, {"p1" : "0.1260E-15 "} ,{"sumps2" :" 2"}, {"p1" : "4E-16 "} ,{"sumps2" :" 1"}, {"p1" : "1.49067E-20 "} ,{"sumps2" :" 5"}, {"p1" : "7.2819E-15 "} ,{"sumps2" :" 7"}, {"p1" : "6.983E-14 "} ,{"sumps2" :" 22"}, {"p1" : "4.4E-20 "} ,{"sumps2" :" 4"}, {"p1" : "9.2640E-17 "} ,{"sumps2" :" 11"}, {"p1" : "293.11E-15 "} ,{"sumps2" :" 4"}, {"p1" : "1.132879E-13 "} ,{"sumps2" :" 4"}, {"p1" : "1.895713E-14 "} ,{"sumps2" :" 19"}, {"p1" : "5.704E-15 "} ,{"sumps2" :" 10"}, {"p1" : "1.22e-14 "} ,{"sumps2" :" 0"}, {"p1" : "5.46883E-15 "} ,{"sumps2" :" 11"}, {"p1" : "1.75993E-18 "} ,{"sumps2" :" 6"}, {"p1" : "8.92E-16 "} ,{"sumps2" :" 8"}, {"p1" : "1.6161E-15 "} ,{"sumps2" :" 9"}, {"p1" : "1.682112E-14 "} ,{"sumps2" :" 14"}, {"p1" : "2.73E-15 "} ,{"sumps2" :" 3"}, {"p1" : "16.660E-15 "} ,{"sumps2" :" 5"}, {"p1" : "9.770E-16 "} ,{"sumps2" :" 4"}, {"p1" : "7.7860E-21 "} ,{"sumps2" :" 5"}, {"p1" : "1.079865E-15 "} ,{"sumps2" :" 17"}, {"p1" : "1.618890E-15 "} ,{"sumps2" :" 14"}, {"p1" : "4.21E-15 "} ,{"sumps2" :" 3"}, {"p1" : "5.6E-14 "} ,{"sumps2" :" 30"}, {"p1" : "0.378E-15 "} ,{"sumps2" :" 1"}, {"p1" : "0.401E-15 "} ,{"sumps2" :" 3"}, {"p1" : "3.0825E-15 "} ,{"sumps2" :" 4"}, {"p1" : "0.0449E-15 "} ,{"sumps2" :" 12"}, {"p1" : "1.68114E-16 "} ,{"sumps2" :" 14"}, {"p1" : "0.139E-15 "} ,{"sumps2" :" 6"}, {"p1" : "0.58E-15 "} ,{"sumps2" :" 24"}, {"p1" : "0.7534E-15 "} ,{"sumps2" :" 5"}, {"p1" : "2.105178E-15 "} ,{"sumps2" :" 7"}, {"p1" : "2.44174E-15 "} ,{"sumps2" :" 11"}, {"p1" : "12.169E-15 "} ,{"sumps2" :" 4"}, {"p1" : "1.89E-17 "} ,{"sumps2" :" 13"}, {"p1" : "3.47811E-15 "} ,{"sumps2" :" 7"}, {"p1" : "9.3E-18 "} ,{"sumps2" :" 4"}, {"p1" : "1.04550E-16 "} ,{"sumps2" :" 6"}, {"p1" : "1.70932E-15 "} ,{"sumps2" :" 9"}, {"p1" : "9.963E-16 "} ,{"sumps2" :" 5"}, {"p1" : "1.279E-15 "} ,{"sumps2" :" 6"}, {"p1" : "4.437E-15 "} ,{"sumps2" :" 8"}, {"p1" : "9.778E-15 "} ,{"sumps2" :" 9"}, {"p1" : "1.25008E-13 "} ,{"sumps2" :" 16"}, {"p1" : "6.799219E-15 "} ,{"sumps2" :" 5"}, {"p1" : "3.5393E-15 "} ,{"sumps2" :" 12"}, {"p1" : "0.0390E-15 "} ,{"sumps2" :" 3"}, {"p1" : "8.1E-16 "} ,{"sumps2" :" 32"}, {"p1" : "1.644E-15 "} ,{"sumps2" :" 1"}, {"p1" : "9.497E-15 "} ,{"sumps2" :" 6"}, {"p1" : "1.7238E-16 "} ,{"sumps2" :" 14"}, {"p1" : "1.60135E-15 "} ,{"sumps2" :" 3"}, {"p1" : "119.94E-15 "} ,{"sumps2" :" 2"}, {"p1" : "7.908E-16 "} ,{"sumps2" :" 5"}, {"p1" : "4.463E-16 "} ,{"sumps2" :" 3"}, {"p1" : "6.32095E-15 "} ,{"sumps2" :" 3"}, {"p1" : "7.26269E-15 "} ,{"sumps2" :" 3"}, {"p1" : "1.362E-14 "} ,{"sumps2" :" 2"}, {"p1" : "1.677E-15 "} ,{"sumps2" :" 10"}, {"p1" : "2.334387E-14 "} ,{"sumps2" :" 5"}, {"p1" : "0.00004912E-15 "} ,{"sumps2" :" 12"}, {"p1" : "8.7494E-14 "} ,{"sumps2" :" 8"}, {"p1" : "1.07E-16 "} ,{"sumps2" :" 9"}, {"p1" : "1.887E-15 "} ,{"sumps2" :" 18"}, {"p1" : "4.63E-16 "} ,{"sumps2" :" 6"}, {"p1" : "1.49E-16 "} ,{"sumps2" :" 3"}, {"p1" : "2.489796E-14 "} ,{"sumps2" :" 4"}, {"p1" : "0.5220E-15 "} ,{"sumps2" :" 3"}, {"p1" : "1.8303E-15 "} ,{"sumps2" :" 2"}, {"p1" : "6.695000E-16 "} ,{"sumps2" :" 17"}, {"p1" : "1.5151E-14 "} ,{"sumps2" :" 2"}, {"p1" : "3.33E-16 "} ,{"sumps2" :" 17"}, {"p1" : "3.59E-15 "} ,{"sumps2" :" 5"}, {"p1" : "0.01E-15 "} ,{"sumps2" :" 2"}, {"p1" : "3.60812E-15 "} ,{"sumps2" :" 4"}, {"p1" : "1.37294E-14 "} ,{"sumps2" :" 10"}, {"p1" : "9.7569E-14 "} ,{"sumps2" :" 4"}, {"p1" : "3.5477E-14 "} ,{"sumps2" :" 5"}, {"p1" : "4.878E-15 "} ,{"sumps2" :" 2"}, {"p1" : "2.50E-16 "} ,{"sumps2" :" 15"}, {"p1" : "8.37E-15 "} ,{"sumps2" :" 8"} ] } </textarea> 

Answer 1

正确，因为obj2.dataset2 [4]是此对象{“ p1”：“ 5.6446E-16”}

Answer 2

Assuming that what you are trying to do is derive the maximum value of the p1 values and present it without using scientific notation, this should work for you.

 // Parse data var data2_JSON = document.getElementById('JSON3').value; var obj2 = JSON.parse(data2_JSON); // Find maximum p1 function getMaxY() { return obj2.dataset2.reduce(function(p, c, i){ // Ignore missing values - Could use (i % 2) here if the order was known to be consistent. return (typeof(c.p1) === 'undefined') ? p : Math.max(p, parseFloat(c.p1, 10)); }, 0); } // var sNum = "1.23e-2"; // alert(parseFloat(sNum)); // alert(parseFloat(obj2.dataset2[4].p1)); // Use toFixed() to ensure the value is not presented with scientific notation alert(getMaxY().toFixed(20)); 

 <textarea id="JSON3"> {"dataset2": [ {"p1" : "2.097E-15 "} ,{"sumps2" :" 12"}, {"p1" : "3.6039E-13 "} ,{"sumps2" :" 5"}, {"p1" : "5.6446E-16 "} ,{"sumps2" :" 14"}, {"p1" : "-4.9850E-20 "} ,{"sumps2" :" 7"}, {"p1" : "4.878E-15 "} ,{"sumps2" :" 2"}, {"p1" : "2.50E-16 "} ,{"sumps2" :" 15"}, {"p1" : "8.37E-15 "} ,{"sumps2" :" 8"} ]} </textarea> 

Answer 3

In the end I found a different solution making a Transform function rendering the data on the width and height variables from the canvas.

http://jsfiddle.net/16t735wr/

var transx = makeTransform([minlogP0, maxlogP0], [mingraphx, maxgraphx]);
var transy = makeTransform([minlogP1, maxlogP1], [maxgraphy, mingraphy]);

// function to create the needed linear transforms
// note from and to are two element arrays (see below):
function makeTransform(from, to){
    // determine a and b in terms of from[0], from[1], to[0] and to[1]
    var x1 = from[0];
    var x2 = from[1];
    var y1 = to[0];
    var y2 = to[1];

    var a = (y1 - y2) / (x1 - x2);
    var b = y1 - a * x1;

    return function(x){return a * x + b;};
}