Method parseForStatement

src/parser.ts:2200–2347

()

    // https://tc39.github.io/ecma262/#sec-for-in-and-for-of-statements

    parseForStatement(): Node.ForStatement | Node.ForInStatement | Node.ForOfStatement {
        let init: any = null;
        let test: Node.Expression | null = null;
        let update: Node.Expression | null = null;
        let forIn = true;
        let left, right;

        const node = this.createNode();
        this.expectKeyword('for');
        this.expect('(');

        if (this.match(';')) {
            this.nextToken();
        } else {
            if (this.matchKeyword('var')) {
                init = this.createNode();
                this.nextToken();

                const previousAllowIn = this.context.allowIn;
                this.context.allowIn = false;
                const declarations = this.parseVariableDeclarationList({ inFor: true });
                this.context.allowIn = previousAllowIn;

                if (declarations.length === 1 && this.matchKeyword('in')) {
                    const decl = declarations[0];
                    if (decl.init && (decl.id.type === Syntax.ArrayPattern || decl.id.type === Syntax.ObjectPattern || this.context.strict)) {
                        this.tolerateError(Messages.ForInOfLoopInitializer, 'for-in');
                    }
                    init = this.finalize(init, new Node.VariableDeclaration(declarations, 'var'));
                    this.nextToken();
                    left = init;
                    right = this.parseExpression();
                    init = null;
                } else if (declarations.length === 1 && declarations[0].init === null && this.matchContextualKeyword('of')) {
                    init = this.finalize(init, new Node.VariableDeclaration(declarations, 'var'));
                    this.nextToken();
                    left = init;
                    right = this.parseAssignmentExpression();
                    init = null;
                    forIn = false;
                } else {
                    init = this.finalize(init, new Node.VariableDeclaration(declarations, 'var'));
                    this.expect(';');
                }
            } else if (this.matchKeyword('const') || this.matchKeyword('let')) {
                init = this.createNode();
                const kind = this.nextToken().value as string;

                if (!this.context.strict && this.lookahead.value === 'in') {
                    init = this.finalize(init, new Node.Identifier(kind));
                    this.nextToken();
                    left = init;
                    right = this.parseExpression();
                    init = null;
                } else {
                    const previousAllowIn = this.context.allowIn;
                    this.context.allowIn = false;
                    const declarations = this.parseBindingList(kind, { inFor: true });