src/xblocks/block.js
function lifecycleInserted() {
    if (this[ Constants.INSERTED ]) {
        return;
    }

    blockInit(this);

    this[ Constants.INSERTED ] = true;

    const isScriptContent = Boolean(this.querySelector('script'));

    // asynchronous read content
    // <xb-test><script>...</script><div>not found</div></xb-test>
    if (isScriptContent) {
        lazy(blockCreateLazy, this);

    } else {
        blockCreate(this);
    }
}
function lifecycleInserted() {
    if (this[ Constants.INSERTED ]) {
        return;
    }

    blockInit(this);

    this[ Constants.INSERTED ] = true;

    const isScriptContent = Boolean(this.querySelector('script'));

    // asynchronous read content
    // <xb-test><script>...</script><div>not found</div></xb-test>
    if (isScriptContent) {
        lazy(blockCreateLazy, this);

    } else {
        blockCreate(this);
    }
}
The callback of the insert in DOM.
@this HTMLElement
@private