Excel tables implemented by less than 30 lines of JS Code

JQuery is not irreplaceable for Excel tables implemented by less than 30 lines of JS Code

A foreign programmer shows an Excel table application written by native JS that does not rely on third-party libraries. It has the following features:

• Implemented by less than 30 lines of native JavaScript code
• Independent from third-party Libraries
• Excel-style semantic analysis (the formula starts with "=)
• Any expression (= A1 + B2 * C3) is supported)
• Prevent loop reference
• LocalStorage-based Automatic local persistent Storage

Effect display:

Code Analysis:

CSS, HTML core only one line:

<table></table>

JavaScript code:

for (var i=0; i<6; i++) {    var row = document.querySelector("table").insertRow(-1);    for (var j=0; j<6; j++) {        var letter = String.fromCharCode("A".charCodeAt(0)+j-1);        row.insertCell(-1).innerHTML = i&&j ? "" : i||letter;    }}var DATA={}, INPUTS=[].slice.call(document.querySelectorAll("input"));INPUTS.forEach(function(elm) {    elm.onfocus = function(e) {        e.target.value = localStorage[e.target.id] || "";    };    elm.onblur = function(e) {        localStorage[e.target.id] = e.target.value;        computeAll();    };    var getter = function() {        var value = localStorage[elm.id] || "";        if (value.charAt(0) == "=") {            with (DATA) return eval(value.substring(1));        } else { return isNaN(parseFloat(value)) ? value : parseFloat(value); }    };    Object.defineProperty(DATA, elm.id, {get:getter});    Object.defineProperty(DATA, elm.id.toLowerCase(), {get:getter});});(window.computeAll = function() {    INPUTS.forEach(function(elm) { try { elm.value = DATA[elm.id]; } catch(e) {} });})();

In fact, we can see from the above that the core steps use EMEAScript5 and HTML5 features, such:

QuerySelectorAll: Provides queries similar to the jQuery selector. Therefore, a third-party JS Library such as jQuery is not required.

var matches = document.querySelectorAll("div.note, div.alert");

DefineProperty provides the Java get and set access/set preprocessing methods for classes, as well as other configuration attributes, such as configuration or enumeration.

Object.defineProperty(o, "b", {get : function(){ return bValue; },                               set : function(newValue){ bValue = newValue; },                               enumerable : true,                               configurable : true});

Original article jsfiddle.net