Learn JS DataGetting Started (Learn JS Data)Reading in Data (Learn JS Data)Combining Data (Learn JS Data)Summarizing Data (Learn JS Data)Iterating Over and Reducing Data (Learn JS Data)Grouping Data (Learn JS Data)Working with Strings (Learn JS Data)Regular Expressions (Learn JS Data)Working with Time (Learn JS Data)
Checking Data Assumptions (Learn JS Data)
function assert(isTrue, message) {
if(!isTrue) {
return message;
}
return null;
}
data = [
{ name: "Dan", age: 23, superhuman: false },
{ name: "Sleepwalker", age: NaN, superhuman: "TRUE" }
]
function checkDataContent(data) {
return data.reduce((arr, d) => {
const dString = JSON.stringify(d);
let msgs = [];
msgs.push(assert(_.isString(d.name), dString + " has a bad name - should be a string"));
msgs.push(assert(_.isNumber(d.age), dString + " has a bad age - should be a number"));
msgs.push(assert(!_.isNaN(d.age), dString + " has a bad age - should not be NaN"));
msgs.push(assert(_.isBoolean(d.superhuman), dString + " has a bad superhuman - should be boolean"));
return arr.concat(msgs.filter(d => d !== null))
}, [])
}
function checkDataShape(data) {
let msgs = [];
msgs.push(assert(data.length > 0, "data is empty"));
msgs.push(assert(data.length > 4, "data is too small"));
var keys = Object.keys(data[0]);
msgs.push(assert(keys.length === 4, "wrong number of columns"));
return msgs.filter(d => d !== null);
}
_.isEqual({ tea: 'green' }, { tea: 'green' })
_.isEqual({ tea: 'earl' }, { tea: 'green' })
_ = require("lodash")
Purpose-built for displays of data
Observable is your go-to platform for exploring data and creating expressive data visualizations. Use reactive JavaScript notebooks for prototyping and a collaborative canvas for visual data exploration and dashboard creation.
