kylelambert101

// indexOf returns the first index of a matching value, so this filters out repeated values after the first instance
foo.filter((value,index,self) => self.indexOf(value) === index)

kylelambert101

''' How to work with JSON files and strings in Python '''
import json

# Load a JSON file
with open(filepath) as f:
    data = json.load(f)

# Save a dict as json
with open(filepath) as f:
    json.dump(foo)

kylelambert101

/**
 * Name and dataType of a property on an object
 */
export type TypedProperty = {
  name: string;
  dataType: string;
};

/**
 * Get the name and datatype of all properties of an object

kylelambert101

// Parse a string into a JSON object
const obj = JSON.parse(myString);

// Stringify an object
// Straight up, no formatting
const str1 = JSON.stringify(obj);

// Pretty-print the JSON with indent of 4
const str2 = JSON.stringify(obj, undefined, 4);

kylelambert101

// To flatten a JS array of arrays (a.k.a get a master array with all values from children)...

// flat is newer - not available in IE
const foo = myArray.flat();

// reduce is another option
const bar = myArray.reduce((allData,currentArray) => allData.concat(currentArray));

kylelambert101

from os import path

result = path.exists(myPath)

# Check whether it is specifically a file
result = path.isfile(myPath)

kylelambert101

# Capture all arguments
args =  sys.argv

# Capture only first argument
arg = sys.argv[0]

# Capture all arguments after the first
other_args = sys.argv[1:]

kylelambert101

for key, value in myDict.items():
    print(f'Key is {key}, value is {value}')

kylelambert101

# See https://docs.python.org/3/library/datetime.html#strftime-and-strptime-format-codes
from datetime import datetime

dateString = "2020-05-31"

# parse a string into a date
myDateTime = datetime.strptime(dateString, '%Y-%m-%d')

# if you want to strip out time
myDate = myDateTime.date()

kylelambert101

// Use this custom hook when you are trying to trace why a component is re-rendering
const useTraceUpdate = (componentName: string, props: any): void => {
  // Capture previous prop state
  const prev = React.useRef(props);
  React.useEffect(() => {
    // Check all field/value pairs of the new props for changes
    const changedProps = Object.entries(props).reduce(
      (changeSummary, [fieldName, currentValue]) => {
        const previousValue = Reflect.get(prev.current, fieldName);
        return previousValue === currentValue