Qt Quick polyfills for Array.flat, String.endsWith, and String.startsWith

mycode.js

.import 'polyjank.js' as PJ

MyControl.qml

import 'polyjank.js' as PJ

polyjank.js

.pragma library

Array.prototype.flat = function(depthArg=1) {
    const getElems = function(arr, elems=[]) {
        for( let a of arr )
        {
            if( typeof a === 'object' )
                elems = getElems(a, elems);
            else
                elems.push(a);
        }
        return elems;
    };

    // depthArg is ignored because who even uses it anyway.
    return getElems(this);
}

String.prototype.endsWith = function(wut) {
    return this.substr( this.length-wut.length ) === wut;
}

String.prototype.startsWith = function(wut) {
    return this.substr( 0, wut.length ) === wut;
}