Function deepCompareReturnPrev

frontend/util/util.ts:71–81

(key: any, newValue: any)

// key must be a suitable weakmap key.  pass the new value
// it will return the prevValue (for object equality) if the new value is deep equal to the prev value
function deepCompareReturnPrev(key: any, newValue: any): any {
    if (key == null) {
        return newValue;
    }
    const previousValue = prevValueCache.get(key);
    if (previousValue !== undefined && JSON.stringify(newValue) === JSON.stringify(previousValue)) {
        return previousValue;
    }
    prevValueCache.set(key, newValue);
    return newValue;
}

// works for json-like objects (arrays, objects, strings, numbers, booleans)
function jsonDeepEqual(v1: any, v2: any): boolean {